Tumor-infiltrating dendritic cells in adenocarcinomas of the breast: a study of 143 neoplasms with a correlation to usual prognostic factors and to clinical outcome

Dendritic cells (DC) are the most potent antigen-presenting cells, and induce antigen-specific immune responses. Infiltration of tumors by DC is thought to reflect the interaction between the host immune system and tumor cells. Tumor-infiltrating DC (TIDC) are believed to evolve into tumor-antigen pulsed cells and then to migrate to local lymph nodes, where they activate anti-tumor immune responses. Indirect clinical evidence supporting this theory is provided by studies showing that high TIDC densities are associated with favorable prognosis in some tumor types. In the present study, we evaluated 143 primary breast adenocarcinomas for the presence of DC, using immunohistochemistry with the anti-S100 protein antibody. We analyzed the relationship between the degree of infiltration by S100+ TIDC and the usual prognostic factors and clinical outcome. The results show that 42% of breast adenocarcinomas contain S100 TIDC. The number of S100+ TIDC varies according to the grade of tumors as follows: GRIII > GRII > GRI. A relationship is also found between S100+ TIDC and tumor size, lymph-node involvement, estrogen/progesterone receptor status and age. However, the presence of S100+ TIDC, even at the highest density, was not correlated with metastasis-free survival or overall survival.

Implication of proteasome in estrogen receptor degradation

In MCF-7 breast cancer cells, estradiol (E2) and pure antiestrogen RU 58668 down-regulate the estrogen receptor (ER). Interestingly, the protein synthesis inhibitor cycloheximide (CHX) abrogated solely the effect of E2 suggesting a selective difference in the degradation of the receptor induced by estrogenic and antiestrogenic stimulations. A panel of lysosome inhibitors (i.e. bafilomycin, chloroquine, NH4Cl, and monensin), calpain inhibitors (calpastatin and PD 150606) and proteasome inhibitors (lactacystin and proteasome inhibitor I) were tested to assess this hypothesis. Among all inhibitors tested, lactacystin and proteasome inhibitor I were the sole inhibitors to abrogate the elimination of the receptor induced by both E2 and RU 58668; this selective effect was also recorded in cells prelabeled with [3H]tamoxifen aziridine before exposure to these ligands. Hence, differential sensitivity to CHX seems to be linked to the different mechanisms which target proteins for proteasome-mediated destruction. Moreover, the two tested proteasome inhibitors produced a slight increase of ER concentration in cells not exposed to any ligand, suggesting also the involvement of proteasome in receptor turnover.

In vitro intrathymic differentiation kinetics of human fetal liver CD34+CD38- progenitors reveals a phenotypically defined dendritic/T-NK precursor split

Human CD34+CD38- hematopoietic precursor cells from fetal liver are able to develop into T, NK, and dendritic cells in a hybrid human/mouse fetal thymic organ culture (FTOC). In this report, we pay particular attention to the early events in differentiation of these precursor cells. We show that the CD34+CD38- precursor cells, which are CD4-CD7-cyCD3-HLA-DR-/++ (cy, cytoplasmatic), differentiate into a CD4+ population that remained CD7-cyCD3-HLA-DR++ and a CD4- population that expressed CD7 and cyCD3. The CD4+CD7-cyCD3- cells differentiate into phenotypically and functionally mature dendritic cells, but do not differentiate into T or NK cells. The CD4-CD7+cyCD3+ population later differentiates into a CD4+CD7+cyCD3+HLA-DR- population, which has no potential to differentiate into dendritic cells but is able to differentiate into NK cells and gammadelta and alphabeta T lymphocytes. These findings support the notion that the T/NK split occurs downstream of the NK/dendritic split.

In Vitro Intrathymic Differentiation Kinetics of Human Fetal Liver CD34+CD38− Progenitors Reveals a Phenotypically Defined Dendritic/T-NK Precursor Split

Human CD34+CD38− hematopoietic precursor cells from fetal liver are able to develop into T, NK, and dendritic cells in a hybrid human/mouse fetal thymic organ culture (FTOC). In this report, we pay particular attention to the early events in differentiation of these precursor cells. We show that the CD34+CD38− precursor cells, which are CD4−CD7−cyCD3−HLA-DR−/++ (cy, cytoplasmatic), differentiate into a CD4+ population that remained CD7−cyCD3−HLA-DR++ and a CD4− population that expressed CD7 and cyCD3. The CD4+CD7−cyCD3− cells differentiate into phenotypically and functionally mature dendritic cells, but do not differentiate into T or NK cells. The CD4−CD7+cyCD3+ population later differentiates into a CD4+CD7+cyCD3+HLA-DR− population, which has no potential to differentiate into dendritic cells but is able to differentiate into NK cells and γδ and αβ T lymphocytes. These findings support the notion that the T/NK split occurs downstream of the NK/dendritic split.

Estrogenic and anti-estrogenic regulation of estrogen receptor in MCF-7 breast-cancer cells: comparison of immunocytochemical data with biochemical measurements

Data from immunocytochemical assessment of estrogen receptor (ER) regulation in MCF-7 cells under estrogenic and anti-estrogenic stimulation were compared with those obtained by enzyme immunoassay (Abbott ER-EIA). Similar trends were observed, although ER level variations were less marked when assessed immunocytochemically. We confirmed reports of ER disappearance in the presence of estrogens (Es; E2 and DES) and pure anti-estrogens (AEs; RU 58,668 and ICI 164,384) as well as its increase with partial AEs (4-OH-TAM and RU 39,119). E2-induced ER down-regulation was partly blocked by actinomycin D (AMD), okadaic acid (OK) and cycloheximide (CHX) when assessed by these 2 methods. Down-regulation by pure AEs was not impeded by CHX, indicating that they operate differently from Es (i.e., transformation of ER to a form sensitive to constitutive degradation activity). In situ pre-labeling of the cells with [3H]TAZ indicated that all investigated ligands eliminate pre-existing ER through binding to newly synthetized receptors, since [3H]TAZ co-valently associates with ER; E2 and RU 58,668 were more effective than 4-OH-TAM in this regard. CHX blocked ER disappearance even in the presence of pure AEs, which is in contrast to the data established with cells not pre-exposed to [3H]TAZ. Nuclear location of [3H]TAZ-ER complexes may explain this discrepancy, since pure AE-ER complexes were reported to be incapable of nuclear translocation.

Exchange of bound estrogens and antiestrogens in MCF-7 cells: evidence for ligand-induced stable configurations of the estrogen receptor

Estrogens and antiestrogens promote specific conformations of the estrogen receptor (ER). To analyze the influence of such configurations on the stability of the ligand-ER complexes, MCF-7 breast cancer cells were exposed for 1 h to either [3H]E2 or an unlabeled estrogen or antiestrogen (E2, DES, E1, BP; OH-Tam, RU 39,411, ICI 164,384, RU 58,668); mutual exchange rates of bound compounds (i.e., [3H]E2-->ligand; ligand-->[3H]E2) were then analyzed in cell extracts by measuring [3H]E2. Addition of cycloheximide (CHX) to the incubation medium eliminated the potential interference of E2-induced ER loss. Extracts from control untreated cells were labeled with [3H]E2 or one of these various ligands and similarly submitted to exchange. Displacement of bound compounds occurred at moderate temperature (18 degrees C) but not at 4 degrees C. Remarkably, exchange proceeded at a lower rate in extracts from cells preincubated with [3H]E2 or a ligand. Antiestrogens RU 39,411 and RU 58,668 appeared especially refractory to displacement. Such low exchange rates were also recorded in experiments conducted on whole cells although to a higher extent than in extracts from preincubated cells. Enzyme immunoassays demonstrated that absence of major exchange could not be attributed to ER loss. Moreover, displacement of bound ligands appeared independent of their binding affinity for the receptor. These data suggest that estrogen and antiestrogen binding is stabilized by at least one factor (coactivators or corepressors) thus fixing the receptor molecules in a configuration that is relatively resistant to subsequent exchange. FPLC and PgR induction revealed that a significant proportion of ER maintained in a sufficiently flexible status was still able to exchange and transduce the transcriptional message of the displacer ligand.

4-iodotamoxifen aziridine, a new affinity labeling agent for the rapid detection of estrogen receptor isoforms

We describe the simple and fast preparation of a new radioiodinated probe for the detection of the estrogen receptor (ER) and its isoforms. Iodotamoxifen aziridine was labeled with iodine 125 ([125I]TAZ) in position 4 of the alpha aromatic ring. The yield was high (>75%), the label was stable and the specific activity was near optimal (1900-2170 Ci/mmol). The apparent relative binding affinity of the probe to a recombinant human ER (hER) was high (RBA = 35 vs estradiol = 100). Electrophoretic studies (SDS-PAGE) with this hER indicated the high potency of [125I]TAZ at very low concentration (<1 nM) to reveal ER bands after a short exposure time (1-4 days). Competition between this probe and various compounds as well as chemical treatments of the ER with SH-reactive chemicals, demonstrated the labeling specificity. Analysis of cytosols from a panel of cell lines and various rat reproductive organs displayed characteristic ER bands (67, 50 and 37 kDa) suppressed by unlabeled E2. Detection in nonreproductive organs of 43 kDa E2-nondisplaceable peptide raised the question upon the presence of altered and/or variant ERs in many tissues. Data concerning human breast cancer cytosols were in complete accordance with those established with [3H]TAZ: high ER polymorphism in most ER-positive samples and peculiar forms (mainly 43 kDa) in ER-negative samples. Hence, [125I]TAZ appears especially useful for the detection of altered ER or related peptides in breast cancers.

Evolution towards hormone independence of the MXT mouse mammary tumor is associated with a gradual change in its estrogen receptor molecular polymorphism

Using a method based on [3H]tamoxifenaziridine ([3H]TAZ) labeling, sequential immunoadsorption with anti-ER monoclonal antibodies, sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and fluorography, we observed a striking change inthe estrogen receptor (ER) electrophoresis pattern of the transplantable MXT mouse mammary tumor. Early, ER "rich" tumors (approximately 100 fmol/mg prot) displayed classical cytosolic 67 and 50 KDa bands. These bands disappeared in favor of a "cytosolic" 35 KDa band during progression towards undifferentiated ER "poor" tumors (approximately 25 fmol/mg prot). Although we can not rule out that this 35 KDa peptide results from in vivo ER proteolysis, it seems unique in view of the following: 1. It is immunoadsorbed not only by an anti-ER monoclonal antibody (H-222) directed to the hormone-binding domain, but also by an anti-ER monoclonal antibody (H-226) which interacts with an epitope in the A/B region close to the DNA-binding domain and is mainly exposed under activation conditions. 2. It does not bind [3H]estradiol([3H]E2) and a tentative to restore its [3H]E2 binding capacity with calmodulin and ATP was unsuccessful. The observation of similar approximately 35 KDa ERs in the nuclear fraction of early tumor transplants and in control uterus suggests that this peptide is already in an activated form. Structural alterations of ER and/or associated "anchorage" nuclear proteins may beat the origin of its cytosolic localization. Moreover, the fact that the addition of calmodulin and ATP to late MXT transplants cytosols fails to increase their [3H]E2 binding capacity indicates that the low ER content of these tumors does not result from a deficiency in the phosphorylation status of the receptor.

Length increase of the side chain of idoxifene does not improve its antagonistic potency in breast-cancer cell lines

Linkage of specific residues onto steroidal estrogens through a long aliphatic side chain leads to "pure antiestrogens" devoid of residual estrogenic activity. Therefore, we assessed whether an increase in the length of the side chain of the triphenylethylenic antiestrogen idoxifene might increase its antagonistic potency. Culture of MCF-7 and tamoxifen-resistant variant RTX6 cells in the presence of CB 7675, a (CH2)8 derivative of idoxifene [(CH2)2], ruled out this possibility. This compound partly blocked MCF-7 cell growth only at 10(-6) M to almost the same extent as tamoxifen and failed to inhibit the growth of RTX6 cells, whereas the pure antiestrogen RU 58 668 was effective on both cell lines at much lower concentration. This absence of improvement was reflected in the observation of an efficiency for down-regulating progesterone receptor no better than that of tamoxifen. Pure antiestrogens are known to down-regulate the estrogen receptor, whereas triphenylethylenic antiestrogens up-regulate the receptor; CB 7675 behaves as the latter in agreement with its lack of strong antagonistic activity.

Human thymocytes become lineage committed at an early postselection CD69+ stage, before the onset of functional maturation

Mature functional CD4 or CD8 single positive (SP) thymocytes differentiate from immature CD4+ 8+ double positive (DP) precursors through a process of positive selection and terminal differentiation. To study CD4/CD8 lineage commitment, human postselection CD69+ thymocytes were separated into distinct subpopulations based on the differential expression of CD27, CD1, and CD45RA/RO. We demonstrate that these CD69+ subpopulations represent transitional stages of a common differentiation pathway during which CD69+ thymocytes that are initially CD27- CD1+ CD45RA- will sequentially up-regulate CD27, down-regulate CD1, and eventually acquire CD45RA upon maturation. Examination of CD4 and CD8 expression on these CD69+ subsets identified an early postselection CD69+ CD27- CD4SP population that gives rise to both CD4SP and CD8SP mature T cells when cultured in mouse thymus organs. In addition, a CD4+ 8+ DP population was identified that is CD69+ and CD27+, which only gives rise to CD8SP progeny upon culture. Although these results suggest that development of CD4SP and CD8SP cells may proceed through distinct intermediates, examination of active biosynthesis of CD4 and CD8 by the various subsets demonstrated that cells that have selectively terminated CD4 synthesis are already present in the CD27- CD4SP and CD27+ DP populations before culture. These data support a model of thymocyte differentiation whereby the decision of thymocytes to differentiate into one or the other lineage occurs concomitantly with, or very soon after, acquisition of CD69 and before the cells acquire CD27, down-regulate CD1, or acquire functional properties.

Human thymocytes become lineage committed at an early postselection CD69+ stage, before the onset of functional maturation

Mature functional CD4 or CD8 single positive (SP) thymocytes differentiate from immature CD4+ 8+ double positive (DP) precursors through a process of positive selection and terminal differentiation. To study CD4/CD8 lineage commitment, human postselection CD69+ thymocytes were separated into distinct subpopulations based on the differential expression of CD27, CD1, and CD45RA/RO. We demonstrate that these CD69+ subpopulations represent transitional stages of a common differentiation pathway during which CD69+ thymocytes that are initially CD27- CD1+ CD45RA- will sequentially up-regulate CD27, down-regulate CD1, and eventually acquire CD45RA upon maturation. Examination of CD4 and CD8 expression on these CD69+ subsets identified an early postselection CD69+ CD27- CD4SP population that gives rise to both CD4SP and CD8SP mature T cells when cultured in mouse thymus organs. In addition, a CD4+ 8+ DP population was identified that is CD69+ and CD27+, which only gives rise to CD8SP progeny upon culture. Although these results suggest that development of CD4SP and CD8SP cells may proceed through distinct intermediates, examination of active biosynthesis of CD4 and CD8 by the various subsets demonstrated that cells that have selectively terminated CD4 synthesis are already present in the CD27- CD4SP and CD27+ DP populations before culture. These data support a model of thymocyte differentiation whereby the decision of thymocytes to differentiate into one or the other lineage occurs concomitantly with, or very soon after, acquisition of CD69 and before the cells acquire CD27, down-regulate CD1, or acquire functional properties.

Estrogen receptor-negative/progesterone receptor-positive Evsa-T mammary tumor cells: a model for assessing the biological property of this peculiar phenotype of breast cancers

In 1986 we reported the appearance of a progestin binding protein in the human breast cancer cell line Evsa-T, originally described as lacking both estrogen and progesterone receptors (ER and PR). In this report we show that PR of this cell line displays a binding affinity for [3H]ORG 2058 and a sucrose gradient sedimentation profile similar to those ascribed to PR from MCF-7 or T47D breast cancer cell lines. PR from Evsa-T cells is down-regulated by the progestin R-5020 as well as by the two antiprogestins, ZK 112.993 and ZK 98.299, but does not confer growth sensitivity to these compounds. ER remains undetectable by ligand binding assay, enzyme immunoassay and northern blotting. Our Evsa-T clone could be a valuable model for assessing the mechanisms leading the ER-/PR+ phenotype occurring occasionally in breast cancers and frequently in meningiomas.

Decrease of hormone binding capacity of estrogen receptor by calcium

We have addressed the question as to whether calcium may modify the [3H]estradiol ([3H]E2) binding properties of the estrogen receptor (ER). A human recombinant full length ER (yER) expressed in yeast was used to limit the potential interference of ER-associated proteins and proteases present in the target tissues. Ca++ (0.1-10 mM) always produced an important loss of [3H]E2 binding capacity without any effect on the hormone binding affinity of residual receptors. This loss was reflected in a decrease of immunoreactivity for monoclonal antibodies raised against the hormone binding domain. An ER recombinant expressing solely this domain confirmed that the ion operated at this level. Binding of [125I]Z-17 alpha-(2-iodovinyl)-11 beta-chloromethyl estradiol-17 beta (an compound with very high selectivity for ER) as well as [125I]tamoxifen aziridine were similarly affected. Size-exclusion chromatography failed to reveal the emergence of any ER isoforms of low molecular weight rejecting the hypothesis of a Ca(++)-induced proteolysis. In agreement with this conclusion, EDTA reversed the loss of [3H]E2 binding capacity. Phosphoamino acids (PY, PT and PS) partly antagonized the effect of Ca++ suggesting its interaction with phosphoamino acid residues. Worthy of note, the effect of Ca++ appeared more marked when assessed by DCC than HAP assay. The phosphocalcic nature of the HAP matrix may explain this phenomenon which was observed with cytosolic ER from various origins.

Optimization of glottic exposure during intubation of a patient lying supine on the ground

Two methods of endotracheal intubation of patients lying on the ground were compared for ease and speed of intubation and minimization of complications in a crossover study of prehospital-oriented emergency physicians. Intubation of a mannequin was attempted by the physicians in either a left lateral decubitus (LLD) position or a kneeling (K) position, followed by the alternate position. The LLD position afforded more rapid intubation, better glottic visualization, and less dental trauma. Eighty-seven percent of physicians completely visualized the glottis in the LLD position, versus 33% of the K position group. Intubation times were 10.5 versus 14.6 seconds in the LLD and K positions, respectively (P < .001). The LLD position is a more effective position (in a mannequin model) than the K position for intubation of patients found lying on the ground, a frequent situation in prehospital care.

Varying sensitivity of human mammary carcinoma cells to the toxic effect of parvovirus H-1

We have previously demonstrated lysis of non-established cultures of human mammary carcinoma cells by parvovirus H-1, which has little effect on the proliferation of corresponding normal cultures. In the present study, we examined this effect in a number of breast-tumour specimens and found them to differ as to the amplitude of their response to parvoviral attack. We first investigated whether the differences in cell sensitivity to parvovirus infection reflected the differentiation level of the initial tumour. Among the biochemical and anatomopathological indicators of original tumour differentiation, the presence of oestrogenic receptors (ER) was found to have a predictive value as to the sensitivity of derived cultures to the cytopathic effect of H-1 virus. The ER+ tumour-derived cultures showed an increased sensitivity to the lytic effect of H-1 virus compared with the ER-tumour-derived cultures, in spite of similar average proliferation rates for the two types of cultures. The proliferation rate was more heterogeneous among ER+ tumour-derived cultures and, in this group, the faster growing cultures were also the most sensitive. This observation was corroborated by the study of established cell lines retaining ER expression under in vitro culture conditions. Oestradiol was found to increase the sensitivity of these cells to the parvovirus in parallel with induction of proliferation. This effect appeared to be mediated by ER activation, since it was not observed in the ER-negative cell line MDA-MB-231. These data point to the importance of hormonal influences and cellular parameters, notably differentiation and proliferation, in determining the extent to which human cancer cells can be targets for the cytopathic effect of parvoviruses.

Protein synthesis is not implicated in the ligand-dependent activation of the estrogen receptor in MCF-7 cells

In MCF-7 cells, estrogen receptor (ER) elimination occurs rapidly under stimulation with estradiol (E2) at 1 nM ('ER processing'); cycloheximide (CHX) at 50 microM impedes this phenomenon. ER processing is also observed when E2 is removed after the first hour of incubation, indicating that the role of the hormone would be limited to the initiation of this process. When CHX is removed at the same time, receptor processing and, later, the induction of progesterone receptor (PgR) both proceed. The initial estrogenic signal which activates ER is therefore not influenced by CHX. In support of this conclusion, no effect of the drug on E2 binding affinity of residual ER was detected. A similar result was recorded for a series of estrogens and antiestrogens, indicating that CHX exerts no influence on the potential agonistic/antagonistic potency of any ligand. Size-exclusion chromatography (FPLC) revealed that [3H]E2-induced ER activation leads to the cleavage of the native receptor (67 kDa) into low molecular weight isoforms which subsequently become less detectable over time (proteolysis). In the presence of CHX, such ER isoforms persist, confirming the absence of interference of the drug with the activation step. When the cells were prelabelled with [3H]tamoxifen aziridine ([3H]TAZ) before their exposure to E2, ER cleavage could not be detected due to the lack of activation potency of the antiestrogenic ligand. However, the [3H]TAZ-ER complexes were subjected to E2-induced processing; CHX blocked this phenomenon, which is associated with the maintenance of ER synthesis and activation.

Phenotypic and functional maturation of TCR gammadelta cells in the human thymus

In contrast to thymic differentiation of TCR alphabeta cells, differentiation stages of TCR gammadelta cells are largely unknown. This report shows that CD1, a known marker of immature TCR alphabeta thymocytes, was expressed on some postnatal TCR gammadelta thymocytes. Only CD1+ TCR gammadelta thymocytes expressed recombination-activating gene-1 mRNA, and they were shown to differentiate into CD1- TCR gammadelta thymocytes. Functionally, sorted CD1- TCR gammadelta thymocytes proliferated in the presence of immobilized anti-CD3 Ab plus exogenous rIL-2 or rIL-15. Interestingly, in contrast to CD1- TCR alphabeta cells, CD1- TCR gammadelta thymocytes also proliferated extensively when cultured with exogenous rIL-2 or rIL-15 alone. FACS analysis as well as reverse transcription-PCR analysis showed that only CD1- TCR gammadelta thymocytes expressed IL-2Rbeta protein and mRNA. The differential expression of maturation markers, such as CD27, CD45RO, and CD45RA, as a function of expression of CD1 was similar in TCR gammadelta and TCR alphabeta thymocytes. An important exception is the expression of CD4 and CD8. Whereas TCR alphabeta thymocytes are mainly CD4-CD8 double positive at the immature CD1+ stage and CD4 or CD8 single positive at the mature CD1- stage, CD1(bright) TCR gammadelta thymocytes all expressed CD4, but only some of them expressed CD8. Some CD1- TCR gammadelta thymocytes also expressed CD8, but were negative for CD4. Collectively, our data clearly show that CD1 is a useful marker to distinguish immature human TCR gammadelta thymocytes from functional mature gammadelta cells based on recombination-activating gene-1 expression, in vitro differentiation, and phenotypic and functional characteristics.

Phenotypic and functional maturation of TCR gammadelta cells in the human thymus

In contrast to thymic differentiation of TCR alphabeta cells, differentiation stages of TCR gammadelta cells are largely unknown. This report shows that CD1, a known marker of immature TCR alphabeta thymocytes, was expressed on some postnatal TCR gammadelta thymocytes. Only CD1+ TCR gammadelta thymocytes expressed recombination-activating gene-1 mRNA, and they were shown to differentiate into CD1- TCR gammadelta thymocytes. Functionally, sorted CD1- TCR gammadelta thymocytes proliferated in the presence of immobilized anti-CD3 Ab plus exogenous rIL-2 or rIL-15. Interestingly, in contrast to CD1- TCR alphabeta cells, CD1- TCR gammadelta thymocytes also proliferated extensively when cultured with exogenous rIL-2 or rIL-15 alone. FACS analysis as well as reverse transcription-PCR analysis showed that only CD1- TCR gammadelta thymocytes expressed IL-2Rbeta protein and mRNA. The differential expression of maturation markers, such as CD27, CD45RO, and CD45RA, as a function of expression of CD1 was similar in TCR gammadelta and TCR alphabeta thymocytes. An important exception is the expression of CD4 and CD8. Whereas TCR alphabeta thymocytes are mainly CD4-CD8 double positive at the immature CD1+ stage and CD4 or CD8 single positive at the mature CD1- stage, CD1(bright) TCR gammadelta thymocytes all expressed CD4, but only some of them expressed CD8. Some CD1- TCR gammadelta thymocytes also expressed CD8, but were negative for CD4. Collectively, our data clearly show that CD1 is a useful marker to distinguish immature human TCR gammadelta thymocytes from functional mature gammadelta cells based on recombination-activating gene-1 expression, in vitro differentiation, and phenotypic and functional characteristics.

MHC class II molecules are required for initiation of positive selection but not during terminal differentiation of human CD4 single positive thymocytes

Positive selection of T cell precursors is an MHC dependent, multistep process by which functionally mature CD4+8- helper and CD4-8+ cytotoxic single positive (SP) T cells are generated from immature CD4+8+ double positive (DP) thymocytes. We investigated the requirement for TCR/MHC class II interactions during different stages of positive selection of human CD4 SP thymocytes. We show that sorted CD69- CD4+8+ DP preselection thymocytes cultured in fetal thymus lobes of normal mice were subject to positive selection and differentiated to CD3(high) CD69+, mature CD8 SP, and CD4 SP cells. When cultured in thymus lobes from MHC class II-deficient mice, these precursors failed to develop into mature CD4 SP T cells, indicating that in the hybrid cultures, murine MHC class II molecules are required for the development of mature human CD4 SP T cells. We have previously identified CD4 SP intermediate thymocytes that have received at least some of the signals involved in positive selection, since these cells are CD69+, CD3/TCR(high), and CD8beta- but that are still phenotypically and functionally immature. Here we demonstrate that in contrast to preselection thymocytes, these CD4 SP intermediate thymocytes can give rise to phenotypically mature and functionally CD4 SP progeny both in normal and in MHC class II-deficient thymus lobes. These results suggest that TCR/MHC interactions are required for the initial stages of positive selection, but are not essential during terminal differentiation to functionally mature CD4 SP T cells.

MHC class II molecules are required for initiation of positive selection but not during terminal differentiation of human CD4 single positive thymocytes

Positive selection of T cell precursors is an MHC dependent, multistep process by which functionally mature CD4+8- helper and CD4-8+ cytotoxic single positive (SP) T cells are generated from immature CD4+8+ double positive (DP) thymocytes. We investigated the requirement for TCR/MHC class II interactions during different stages of positive selection of human CD4 SP thymocytes. We show that sorted CD69- CD4+8+ DP preselection thymocytes cultured in fetal thymus lobes of normal mice were subject to positive selection and differentiated to CD3(high) CD69+, mature CD8 SP, and CD4 SP cells. When cultured in thymus lobes from MHC class II-deficient mice, these precursors failed to develop into mature CD4 SP T cells, indicating that in the hybrid cultures, murine MHC class II molecules are required for the development of mature human CD4 SP T cells. We have previously identified CD4 SP intermediate thymocytes that have received at least some of the signals involved in positive selection, since these cells are CD69+, CD3/TCR(high), and CD8beta- but that are still phenotypically and functionally immature. Here we demonstrate that in contrast to preselection thymocytes, these CD4 SP intermediate thymocytes can give rise to phenotypically mature and functionally CD4 SP progeny both in normal and in MHC class II-deficient thymus lobes. These results suggest that TCR/MHC interactions are required for the initial stages of positive selection, but are not essential during terminal differentiation to functionally mature CD4 SP T cells.

Antagonism of estrogen receptor and calmodulin association by antiestrogens is not dependent on an interaction with calmodulin

Previously, two antiestrogens estradiol derivatives (3 and 4) bearing the basic side chain of tamoxifen were shown to impede the binding of the estrogen receptor (ER) to calmodulin (CaM)-Sepharose. In this study, the interaction of these and related compounds with calmodulin was examined using the cyclic AMP phosphodiesterase (cAMP-PDE) assay. Neither of the steroids gave any significant inhibition of the calmodulin dependent cAMP-PDE activity up to a final concentration of 20 microM. For comparison, tamoxifen and nafoxidine produced IC50 values of 6.7 microM +/- 1.0 and 7.4 microM +/- 1.1, respectively. In addition, a comparison was made of the activity of some triphenylethylene derivatives against CaM dependent cAMP-PDE and the ER-CaM Sepharose assays, but no relationship was observed. Overall, these results demonstrate that inhibition of the ER-CaM association by various steroidal and triphenylethylene antiestrogens does not relate to antagonism of calmodulin function or their binding affinity for the estrogen receptor.

Tamoxifen-induced estrogen receptor up-regulation in mammary tumor cells is not related to growth inhibition

Treatment of estrogen receptor (ER)-positive mammary tumors with tamoxifen produces a dramatic accumulation of ER in the cell nucleus. We investigated whether this phenomenon might be related to the antitumor activity of the drug. Five tamoxifen derivatives for which an influence on MCF-7 cell growth had previously been established were tested for that purpose; two of them inhibited growth, one was growth-stimulatory, and the remaining two were without significant effect. At 1 microM all compounds up-regulated ER in the cell nucleus after 3 days of culture, suggesting that the ER accumulation does not predict the response to tamoxifen treatment. An analysis of a tamoxifen-resistant clone (RT x 6 cells) under similar experimental conditions led to the same conclusion: the ER level significantly increased in the presence of tamoxifen and its 4-hydroxy metabolite.

Interleukin-7 is a critical growth factor in early human T-cell development

Highly purified human CD34+ fetal liver stem cells differentiate to mature T cells when seeded in vitro into isolated fetal thymic lobes of severe combined immunodeficient (SCID) mice followed by fetal thymus organ culture (FTOC). Here, this chimeric human-mouse FTOC was used to address the role of interleukin-7 (IL-7) and of the alpha chain of the IL-7 receptor (IL-7R alpha) in early human T-cell development. We report that addition of either the monoclonal antibody (MoAb) M25, which neutralizes both human and mouse IL-7, or the MoAb M21, which recognizes and blocks exclusively the human high-affinity alpha-chain of the IL-7R, results in a profound reduction in human thymic cellularity. Analysis of lymphoid subpopulations indicates that a highly reduced number of cells undergo maturation from CD34+ precursor cells toward CD4+CD3-CD1+ progenitor cells and subsequently toward CD4+CD8+ thymocytes. Our results reveal a critical role for IL-7 during early human thymocyte development, and may explain the absence or highly reduced levels of T cells in patients with X-linked SCID. The molecular defect in these patients has been shown to be a mutation in the gamma chain of the IL-2R. Although this gamma chain is not only present in the IL-2R, but also forms an essential part of other cytokine receptors, including IL-4, IL-7, IL-9, IL-13, and IL-15, the T-cell defect in these patients can be explained by the fact that IL-7 is not able to transduce its signal by the molecular defect of the common gamma (gamma c) chain and that IL-7 is indispensable for T-cell development.

Thymic and extrathymic T cell development

The majority of T cells located in peripheral blood, spleen and lymph nodes are dependent on the thymus for proper differentiation and function. Only a minority of T lymphocytes located in these lymphoid organs is thymic-independent. In contrast, a large number of thymus-independent T cells is present in the gut epithelium. This review deals with phenotypic and functional characteristics of T cell development, summarizes the knowledge on the cytokine requirement in this process and describes positive and negative selection. The differences between thymic-dependent and thymic-independent T cells are emphasized, including selection processes, CD4-CD8 expression and the composition of the CD3 complex.

Thymic development of V gamma 3 cells

Several characteristics of V gamma 3 cells are clearly different from those of other T cells. V gamma 3 thymocytes mainly originate from fetal precursor cells and only differentiate efficiently in a fetal thymic environment. Evidence is discussed that the early appearance of V gamma 3 cells is probably due to differential gene accessibility which regulates gene rearrangement. Another characteristic of V gamma 3 cells is the canonical sequence of their T-cell receptor (TCR), which seems to be mainly shaped intracellularly by the combination of targeted gene rearrangement, homology-directed recombination and the absence of terminal deoxynucleotidyl transferase, rather than by cellular selection. Contrary to alpha beta cells, V gamma 3 cells express the Fc epsilon RI gamma chain in their TCR complex and other protein tyrosine kinases are important for their thymic differentiation. Also, expression of several cell surface markers is regulated differently on V gamma 3 cells as compared to alpha beta cells. Collectively, these findings show that V gamma 3 cells are a separate lineage of T cells with unique requirements for proper thymic differentiation and survival.

Calmodulin decreases the estrogen binding capacity of the estrogen receptor

We previously demonstrated the ability of calmodulin (CaM) to decrease the binding affinity of estradiol (E2) to the rat uterine estrogen receptor (ER). We show now that CaM induces a loss of E2 binding capacity especially when ER molecules exhibit a lower binding affinity for the hormone. By Western blotting and [125I]tamoxifen aziridine covalent labeling we found that this CaM-induced loss is not associated with a disappearance of the ER protein. In addition, we were able to demonstrate a CaM-mediated decrease in E2 binding of a human recombinant ER expressing solely its hormone binding domain (HBD, aa 282-595). Hence, CaM can modulate the structure of the HBD of the ER without any involvement of a degradative process, this conformational change is not mediated by other domains of the receptor and/or components of the native ER heterocomplex.

Tamoxifen aziridine labeling of the estrogen receptor-potential utility in detecting biologically aggressive breast tumors

Expression of estrogen receptor (ER) is a helpful predictor of response to endocrine therapy and disease free survival in breast cancer patients. The presence of variant estrogen receptors has been demonstrated at the RNA/DNA level and might represent an escape of tumors from hormonal control mechanisms. However, the demonstration that the corresponding peptides do exist is a real challenge. Denaturing polyacrylamide gel electrophoresis (SDS-PAGE) of covalently bound [3H]tamoxifen aziridine ([3H]TAZ) to ER demonstrates a specific, multiband peptide pattern recognized by anti-ER monoclonal antibodies (anti-ER Mo Abs). The native 66 kDa ER form identified through its hormone binding domain by the H-222 Mo Ab was the most prominent one followed by 50, 35, and 28 kDa forms on fluorography. Such patterns from early human breast tumors were compared to the ones of more advanced disease, namely large primary breast cancers, metastatic lymph nodes, and soft tissue relapses: in these cases, molecular forms of 43 and 35 kDa were identified with a remarkable consistency. The 43 kDa peptide was more frequently identified by the H-226 Mo Ab (which maps a region near the DNA binding domain)-albeit with low labeling intensity as compared to H-222 Mo Ab. In addition, the 43 kDa peptide was inversely correlated to ER levels. This altered ER or related peptide could potentially be a marker of biologically aggressive breast tumors.

Synthesis, structure and biological properties of Z-17alpha-(2-iodovinyl)-11beta-chloromethyl estradiol-17beta (Z-CMIV), a high affinity ligand for the characterization of estrogen receptor-positive tumors

Linkage of a 11beta-chloromethyl group to estradiol-17beta (E2) dramatically increases the binding affinity of the steroid for the estrogen receptor (ER) with the formation of a quasi-irreversible steroid-receptor complex. We have synthesized the two isomers of 11beta-chloromethyl-17alpha-iodovinyl-estradiol (E-CMIV and Z-CMIV) by a novel route. Both derivatives demonstrated high binding affinity and selectivity for ER (RBAs: ER = 820 and 1008; SHBG = 1.2 and 0.25, respectively; E2 = 100). On the basis of X-ray crystallographic data for Z-CMIV and its precursor, we have postulated that Z-CMIV might interact strongly with aromatic amino-acids within a hydrophobic groove of the ER hormone binding domain (HBD) that incorporates pockets corresponding to the 11beta and 17alpha steroid substituents. The binding properties of Z-CMIV labeled with 125I were investigated, especially its ability to detect and quantify altered ER forms with low binding affinity for E2. Sucrose density gradient analysis revealed that Z-CMIV has a higher activation potency than E2 as it converts a higher proportion of non-activated monomers in the cytosol into activated monomers with the potential to dimerize. In in vitro (MCF-7 cells) and in vivo (rat uterus) determinations of estrogenic activity, Z-CMIV was as potent as E2 in increasing progesterone receptor (PgR) concentrations and decreasing ER levels and in stimulating uterine growth. [125I]-Z-CMIV could open the way to new applications in the diagnosis and therapy of ER-positive breast cancers, especially those containing altered (variant) ERs.

Differential effects of interleukin-15 and interleukin-2 on differentiation of bipotential T/natural killer progenitor cells

Bipotential T/natural killer (NK) progenitor cells are destined to differentiate mainly into T cell receptor (TCR) alpha beta and TCR gamma delta cells in a thymic microenvironment, whereas extrathymically they selectively develop into NK cells. The exact environmental conditions that are required for differentiation into these three leukocyte populations are largely unknown. In this report, we have investigated and compared the effect of interleukin (IL)-15 and IL-2 in this process. The IL-15 receptor is composed of the gamma and beta chains of the IL-2 receptor (IL-2R gamma and IL-2R beta) and of a specific alpha chain (IL-15R alpha). Here, it is shown that IL-15 mRNA is mainly expressed in thymic epithelial stromal cells, whereas IL-2 mRNA is exclusively expressed in thymocytes. IL-2R beta-expressing cells were present in the fetal thymus with a CD25-CD44+Fc gamma R+HSA-/low TCR- phenotype, which is characteristic of progenitor cells. These cells also expressed IL-15R alpha messenger RNA. Sorted IL-2R beta + TCR- cells differentiated into TCR alpha beta and TCR gamma delta cells after transfer to alymphoid thymic lobes, whereas culture of the same sorted cells in cell suspension in the presence of IL-15 resulted in the generation of functional NK cells. This shows that IL-2R beta +TCR- cells of the fetal thymus contain bipotential T/NK progenitors. Addition of low concentrations of IL-15 to fetal thymic organ culture (FTOC) resulted in an increase of all T cell subpopulations. The largest expansion occurred in the TCR gamma delta compartment. In contrast, low concentrations of IL-2 did not result in a higher total cell number and did not induce outgrowth of TCR gamma delta cells. High concentrations of IL-15 blocked TCR alpha beta development and shifted differentiation towards NK cells. Differentiation towards TCR gamma delta cells still proceeded. High concentrations of IL-2 similarly induced development into NK cells, but the cell number was fourfold lower than in IL-15 cultures. Importantly, blocking of IL-2R alpha in IL-2-treated FTOC resulted in a drastic increase in cell number, indicating that IL-2R alpha negatively regulates cell expansion. Collectively, these experiments provide direct evidence that IL-15 and IL-2 differentially affect the differentiation of bipotential T/NK progenitors.

Relationship between receptors for epidermal growth factor and steroid hormones in normal, dysplastic and neoplastic canine mammary tissues

The concentrations of receptors for epidermal growth factor (EGF-R), oestrogen (ER) and progesterone (PR) were measured in 108 samples from canine mammary tumours and 132 samples of normal mammary tissue removed surgically from 84 bitches. The history and clinical signs were also recorded. Binding sites of high affinity were detected in 70 per cent of both types of tissue and no significant variations in EGF-R concentrations or positivity were observed with the histology, location, size or number of mammary tumours or the age of the animal. A significant direct correlation (P = 0.002) was observed between the concentrations of ER and EGF-R only in malignant tumours. The concentrations of EGF-R were significantly correlated (P = 0.04) in normal mammary tissues adjacent to and distant from the lesions, but not between normal tissue and tumour tissue. No significant differences were observed in the expression of EGF-R in normal and neoplastic tissues from the same bitches. The direct correlation between the concentrations of EGF-R and ER in malignant tumours could be related to an oestrogen-dependent expression of EGF-R or to a similar pattern of regulation of the receptors.

Estrogenic and antiestrogenic regulation of the half-life of covalently labeled estrogen receptor in MCF-7 breast cancer cells

Effect of estrogens and antiestrogens (AEs) on estrogen receptor (ER) half-life was analyzed in MCF-7 cells by assessing its progressive disappearance after covalent labeling in situ with [3H]tamoxifen aziridine ([3H]TAZ). Cells were incubated for 1 h with 20 nM [3H]TAZ either in the absence or presence of a 500-fold excess of unlabeled estradiol (E2) (non-specific binding). The entire ER population was labeled by this method as established by subsequent incubation of the cells with [125I]E2. [3H]TAZ labeled cells were maintained in culture for additional 5 h in the absence (control) or presence of increasing amounts (0.1 nM - 1 microM) of either a given estrogen (E2, estrone, diethylstilbestrol, bisphenol), a pure AE (RU 58 668, ICI 164 384) or an AE with residual estrogenic activity (RU 39 411, 4-hydroxytamoxifen, keoxifene). The progressive disappearance of nuclear and cytosolic [3H]TAZ-ER complex during 5 h incubation were assessed by their immunoprecipitation with anti-ER monoclonal antibody (H 222) followed by scintillation counting or SDS-PAGE and fluorography. Fading of labeled receptors was extremely slow (approximately 10% loss after 6 h) in absence of any hormone/antihormone indicating a long half-life of the [3H]TAZ-ER complex. Addition of estrogens as well as pure AEs led to a dramatic reduction of the half-life while AEs with residual estrogenic activity were extremely less efficient in this regard providing an explanation for the ability of latter compounds to up-regulate the receptor since they do not affect ER mRNA synthesis and stability. Receptor disappearance induced by estrogens was closely related to their binding affinity for ER. Newly synthesized ER emerged during the treatment with hormones or antihormones seems to be implicated in the phenomenon since [3H]TAZ was covalently bound and could, therefore, not be displaced by these compounds. Induction of synthesis of a short half-life peptide(s) with degradative activity was demonstrated by addition of cycloheximide or puromycine (both at 50 microM) which completely blocked ER disappearance. The fact that no cleavage products of ER were detected by SDS-PAGE suggested a lysosomial hydrolysis. Hence, hormonal modulation of only a part of ERs may down-regulate their total population until it reaches the steady-state level.

Differentiation to T helper cells in the thymus. Gradual acquisition of T helper cell function by CD3+CD4+ cells

We investigated at which point during thymocyte differentiation functions were acquired that are characteristic for mature Th cells. Differentiation from CD3+CD69-, CD4+CD8+ double-positive (DP) cells to terminally differentiated CD3+, CD4+CD8- single-positive (SP) cells was broken down into six discrete stages that were purified by four-color sorting: CD69-CD3+DP (stage 0), CD69+CD27-DP (stage 1), CD69+CD27-CD4+SP (stage 2), CD27+CD1+CD4+SP (stage 3), CD1-CD45RO+CD4+SP (stage 4), and CD1-CD45RO-CD4+SP cells (stage 5). Phenotypically, these stages seem to describe consecutive steps in differentiation from immature stage 0 to the terminally matured stage 5. Functionally, the capacity to proliferate on IL-2 after stimulation was absent in CD69- stage 0 cells, but was acquired gradually during stages 1 to 4. Clonal expandability and the capacity to respond to stimulation with the production of cytokines were acquired later and rather abruptly by CD1- stage 4 and 5 cells. Activation markers such as CD69 expression and in vivo IL-2 gene transcription came up simultaneously at the DP stage and peaked at stage 3 to 4. These data suggest that functional maturation of Th cells occurs over an extended period in differentiation, stages 1 to 4, and coincides with a gradual increase in activation markers. After completion of functional differentiation, at stage 5, in vivo IL-2 mRNA transcription and CD69 expression are down-regulated, and the cells become functionally resting naive T cells expressing CD45RA+.

Differentiation to T helper cells in the thymus. Gradual acquisition of T helper cell function by CD3+CD4+ cells

We investigated at which point during thymocyte differentiation functions were acquired that are characteristic for mature Th cells. Differentiation from CD3+CD69-, CD4+CD8+ double-positive (DP) cells to terminally differentiated CD3+, CD4+CD8- single-positive (SP) cells was broken down into six discrete stages that were purified by four-color sorting: CD69-CD3+DP (stage 0), CD69+CD27-DP (stage 1), CD69+CD27-CD4+SP (stage 2), CD27+CD1+CD4+SP (stage 3), CD1-CD45RO+CD4+SP (stage 4), and CD1-CD45RO-CD4+SP cells (stage 5). Phenotypically, these stages seem to describe consecutive steps in differentiation from immature stage 0 to the terminally matured stage 5. Functionally, the capacity to proliferate on IL-2 after stimulation was absent in CD69- stage 0 cells, but was acquired gradually during stages 1 to 4. Clonal expandability and the capacity to respond to stimulation with the production of cytokines were acquired later and rather abruptly by CD1- stage 4 and 5 cells. Activation markers such as CD69 expression and in vivo IL-2 gene transcription came up simultaneously at the DP stage and peaked at stage 3 to 4. These data suggest that functional maturation of Th cells occurs over an extended period in differentiation, stages 1 to 4, and coincides with a gradual increase in activation markers. After completion of functional differentiation, at stage 5, in vivo IL-2 mRNA transcription and CD69 expression are down-regulated, and the cells become functionally resting naive T cells expressing CD45RA+.

Major molecular weight heterogeneity of estrogen receptor from breast cancer is not related to neoplasia

Recent investigation from our laboratory revealed that the estrogen receptor (ER) from breast cancer is characterized by a high molecular weight polymorphism: SDS-polyacrylamide gel electrophoresis of [3H]-tamoxifen aziridine ([3H]-TAZ) labeled cytosols usually display several bands corresponding to the native receptor (67 KDa) and lower molecular cleavage products. High frequency of such altered receptors was confirmed here by size exclusion FPLC of [125I]-E2 labeled cytosols from a series of 98 breast cancers: on the average, 60% of the ER molecules were strongly degraded (Mr < or = 37 KDa). The absence of transcriptional activating domains (ABC domains) in such receptors was further demonstrated by assessing their ability to bind to hydroxylapatite (HAP). Thus, in presence of 500 mM KCI, 55% of ERs from another series of 54 cytosols failed to strongly adsorb to this phosphocalcic matrix, a characteristic property of receptors without exposed ABC domains. Finally, [3H]-TAZ labeled cytosols from normal uterine tissue and MCF-7 human breast cancer cells growing in nude mice displayed identical multibands electrophoretic patterns revealing in both cases native and cleaved receptors. Since latter receptor forms were never detected in MCF-7 cells growing in monolayer culture, we put forward the hypothesis that they were produced under the action of proteolytic enzymes acting at the time of tissue processing. Hence, most of the truncated receptors detected in human breast cancer cytosols should not be markers of malignancy.

Comparison of estrogen and progesterone receptor expression in normal and tumor mammary tissues from dogs

Concentrations of estrogen (ER) and progesterone (PR) receptors were measured by radioreceptor assay in tumor (n = 319) and normal (n = 166) mammary tissue from 248 bitches. Correlations between ER and PR and between receptor expression in tumor and normal mammary tissue from the same bitches were evaluated. The influence of tumor, clinical, or hormonal variables on receptor expression also was studied. Approximately 80% of tumor and 95% of normal mammary tissue expressed detectable concentrations of ER, PR, or both. Direct correlation was found between ER and PR concentrations in normal and tumor tissues. Median ER concentrations were significantly higher (46 +/- 47 fmol/mg of cytosolic protein vs 27 +/- 24 fmol/mg of cytosolic protein; P = 0.0002) in normal than in tumor tissue. On the other hand, PR concentrations were significantly higher (57 +/- 52 fmol/mg vs 77 +/- 99 fmol/mg; P = 0.03) in tumors (especially benign tumors) than in normal tissue. Poorly differentiated malignant tumors expressed lower concentrations of receptors than did benign or well differentiated malignant tumors. The ER and PR concentrations decreased with increasing size of the lesion. Hormonal status of the bitch significantly (P < 0.05) influenced receptor expression in normal tissue: bitches in the luteal phase of the estrous cycle had higher concentrations of ER (69 +/- 62 fmol/mg) than did ovariectomized bitches (24 +/- 19 fmol/mg) or bitches in anestrus (38 +/- 45 fmol/mg) or the follicular phase (13 +/- 7 fmol/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of distinct stages during the differentiation of human CD69+CD3+ thymocytes and identification of thymic emigrants

During thymocyte development, CD69 expression is induced at an early stage of positive selection. To examine the differentiation of human CD69+CD3+ thymocytes, discrete phenotypes were defined by the relative expression of CD69, CD27, CD1, and CD45RA/RO: CD3+CD69- thymocytes were CD27-CD1+CD45RA-/RO+ (phenotype I), whereas the CD3+ CD69+ population could be subdivided into CD27-CD1+CD45RA-/RA+ (phenotype II), CD27+CD1+CD45RA-/RO+ (phenotype III), CD27+CD1-CD45RA-/dull/RO+ (phenotype IV), and CD27+CD1-CD45RA+/ROdull (phenotype V) thymocytes. Phenotype I thymocytes were CD4+CD8 alpha beta + double positive (DP). Phenotype II thymocytes contained DP and CD4+CD8 alpha dullCD8 beta- cells, whereas phenotype III thymocytes were DP and mostly CD4dullCD8 alpha beta+, indicating that CD27 on DP cells may be a marker for CD8-committed cells. Results obtained with SCID-hu mice, transplanted with human fetal thymus and liver, showed that immature human CD69-CD3+ thymocytes were corticosteroid-sensitive, whereas essentially all CD69+CD3+ cells were resistant. During differentiation of one cohort of corticosteroid-resistant CD69+CD3+ thymocytes, phenotype II and III thymocytes, disappeared within a week, whereas the percentage of phenotype IV and especially V thymocytes increased, suggesting that the latter represent the end stages in differentiation. Recent thymic emigrants in SCID-hu mice were identified as CD69-CD27+CD1-CD45RA-/dull/RO+ or CD45RA+/ROdull cells. Because phenotype IV and phenotype V thymocytes rapidly lose CD69 expression in cell culture, these thymocytes are probably the cells that are exported from the thymus. In conclusion, after the acquisition of CD69, thymocyte differentiation appears to continue in an ordered pattern, and cells that eventually leave the thymus are CD69-CD1-CD45RA+ or CD45RA-/dull.

Characterization of distinct stages during the differentiation of human CD69+CD3+ thymocytes and identification of thymic emigrants

During thymocyte development, CD69 expression is induced at an early stage of positive selection. To examine the differentiation of human CD69+CD3+ thymocytes, discrete phenotypes were defined by the relative expression of CD69, CD27, CD1, and CD45RA/RO: CD3+CD69- thymocytes were CD27-CD1+CD45RA-/RO+ (phenotype I), whereas the CD3+ CD69+ population could be subdivided into CD27-CD1+CD45RA-/RA+ (phenotype II), CD27+CD1+CD45RA-/RO+ (phenotype III), CD27+CD1-CD45RA-/dull/RO+ (phenotype IV), and CD27+CD1-CD45RA+/ROdull (phenotype V) thymocytes. Phenotype I thymocytes were CD4+CD8 alpha beta + double positive (DP). Phenotype II thymocytes contained DP and CD4+CD8 alpha dullCD8 beta- cells, whereas phenotype III thymocytes were DP and mostly CD4dullCD8 alpha beta+, indicating that CD27 on DP cells may be a marker for CD8-committed cells. Results obtained with SCID-hu mice, transplanted with human fetal thymus and liver, showed that immature human CD69-CD3+ thymocytes were corticosteroid-sensitive, whereas essentially all CD69+CD3+ cells were resistant. During differentiation of one cohort of corticosteroid-resistant CD69+CD3+ thymocytes, phenotype II and III thymocytes, disappeared within a week, whereas the percentage of phenotype IV and especially V thymocytes increased, suggesting that the latter represent the end stages in differentiation. Recent thymic emigrants in SCID-hu mice were identified as CD69-CD27+CD1-CD45RA-/dull/RO+ or CD45RA+/ROdull cells. Because phenotype IV and phenotype V thymocytes rapidly lose CD69 expression in cell culture, these thymocytes are probably the cells that are exported from the thymus. In conclusion, after the acquisition of CD69, thymocyte differentiation appears to continue in an ordered pattern, and cells that eventually leave the thymus are CD69-CD1-CD45RA+ or CD45RA-/dull.

Antiestrogenic activity of two 11 beta-estradiol derivatives on MCF-7 breast cancer cells

Two 11 beta-derivatives of estradiol (E2) were tested for their potential antiestrogenic activity in the MCF-7 breast cancer model: one contained a phenoxydimethylaminoethyl side-chain (RU 39,411), the other a pentafluoropentylsulfinyl side-chain (RU 58,668). The former compound displayed mixed estrogenic/antiestrogenic properties, while the latter indicated only an antiestrogenic activity. Both the compounds produced a growth inhibition of MCF-7 cells at doses related to their binding affinity for the estrogen receptor (ER); E2 suppressed this inhibition. The compounds also down-regulated the estrogen binding capacity of the cells but failed to reduce ER mRNA levels, indicating that the grafting of their side-chains prevented this antagonistic effect usually observed with steroidal estrogens. Assessment of ER levels by enzyme immunoassay revealed a marked increase with RU 39,411 and a decrease with RU 58,668; different mechanisms of action should, therefore, be considered. Finally, the estrogenic activity of RU 39,411 was demonstrated by its strong ability to induce synthesis of the progesterone receptor; RU 58,668 failed to display this agonistic activity.

Influence of TGF-beta on murine thymocyte development in fetal thymus organ culture

TGF-beta is a multifunctional growth regulator that can either inhibit or stimulate the growth and differentiation of lymphocytes. For several cell types the effect of TGF-beta was found to correlate with the differentiation stage of the cells. We have studied the influence of TGF-beta on the differentiation of murine thymocytes by evaluating the effect of TGF-beta on the generation of thymocyte subpopulations in fetal thymus organ culture. TGF-beta inhibited the growth and differentiation of CD4-CD8- double-negative thymocytes. In the CD4-CD8- double-negative cell population, most cells remained CD44+CD25-, with CD44+CD25+ and CD44-CD25- subpopulations dramatically decreased in cell numbers. The accumulation of cells with a phenotype characteristic of cells in early stage of differentiation suggests a block at very early transition steps. These observations were confirmed in experiments with precursor cells from fetal liver transferred to 2-deoxyguanosine-treated alymphoid thymic lobes, inasmuch as addition of TGF-beta caused a complete inhibition of T cell development. Differentiation into CD4+CD8+ double-positive thymocytes and CD4+ single-positive thymocytes was impaired because these cell numbers were greatly reduced. In contrast, the CD8+ single-positive subpopulation retained normal cell numbers. This CD8+ population had characteristics of a mature subset as the cells expressed CD8 beta and high levels of TCR-alpha beta and CD3. This TCR-alpha beta + cell population was not actively dividing, suggesting that these cells arise de novo by differentiation.

Influence of TGF-beta on murine thymocyte development in fetal thymus organ culture

TGF-beta is a multifunctional growth regulator that can either inhibit or stimulate the growth and differentiation of lymphocytes. For several cell types the effect of TGF-beta was found to correlate with the differentiation stage of the cells. We have studied the influence of TGF-beta on the differentiation of murine thymocytes by evaluating the effect of TGF-beta on the generation of thymocyte subpopulations in fetal thymus organ culture. TGF-beta inhibited the growth and differentiation of CD4-CD8- double-negative thymocytes. In the CD4-CD8- double-negative cell population, most cells remained CD44+CD25-, with CD44+CD25+ and CD44-CD25- subpopulations dramatically decreased in cell numbers. The accumulation of cells with a phenotype characteristic of cells in early stage of differentiation suggests a block at very early transition steps. These observations were confirmed in experiments with precursor cells from fetal liver transferred to 2-deoxyguanosine-treated alymphoid thymic lobes, inasmuch as addition of TGF-beta caused a complete inhibition of T cell development. Differentiation into CD4+CD8+ double-positive thymocytes and CD4+ single-positive thymocytes was impaired because these cell numbers were greatly reduced. In contrast, the CD8+ single-positive subpopulation retained normal cell numbers. This CD8+ population had characteristics of a mature subset as the cells expressed CD8 beta and high levels of TCR-alpha beta and CD3. This TCR-alpha beta + cell population was not actively dividing, suggesting that these cells arise de novo by differentiation.

Stimulation of TCR V gamma 3 cells by gram-negative bacteria

A distinct feature of most murine TCR-gamma delta cells is that they localize in epithelial tissues that cover the internal and external surface of the body. Therefore, TCR-gamma delta cells have been hypothesized to represent a first line of defense against invading pathogens. In this study, it is shown that TCR V gamma 3 cells are activated to produce cytokines upon interaction with Gram-negative bacteria, whereas Gram-positive bacteria have no effect. Accessory cells are not required. LPS of Gram-negative bacteria is shown to be the stimulating structure for TCR V gamma 3 cells, as the stimulation is inhibited by addition of polymyxin B or anti-LPS Ab and as purified LPS stimulates V gamma 3 T cells. Blocking of the V gamma 3 TCR does not inhibit stimulation by Gram-negative bacteria, whereas suboptimal triggering of the TCR is synergistic. These results demonstrate that LPS is an important stimulus for TCR V gamma 3 cells. This indicates that skin-located V gamma 3 T cells might play a role in the defense against Gram-negative bacteria.

Stimulation of TCR V gamma 3 cells by gram-negative bacteria

A distinct feature of most murine TCR-gamma delta cells is that they localize in epithelial tissues that cover the internal and external surface of the body. Therefore, TCR-gamma delta cells have been hypothesized to represent a first line of defense against invading pathogens. In this study, it is shown that TCR V gamma 3 cells are activated to produce cytokines upon interaction with Gram-negative bacteria, whereas Gram-positive bacteria have no effect. Accessory cells are not required. LPS of Gram-negative bacteria is shown to be the stimulating structure for TCR V gamma 3 cells, as the stimulation is inhibited by addition of polymyxin B or anti-LPS Ab and as purified LPS stimulates V gamma 3 T cells. Blocking of the V gamma 3 TCR does not inhibit stimulation by Gram-negative bacteria, whereas suboptimal triggering of the TCR is synergistic. These results demonstrate that LPS is an important stimulus for TCR V gamma 3 cells. This indicates that skin-located V gamma 3 T cells might play a role in the defense against Gram-negative bacteria.

Cytokine dependence of V gamma 3 thymocytes: mature but not immature V gamma 3 cells require endogenous IL-2 and IL-7 to survive--evidence for cytokine redundancy

It has previously been described that V gamma 3 cells can proliferate extensively in vitro in the presence of different cytokines. Here, the role of cytokines in the maintenance of V gamma 3 cells in the thymus has been determined. Culture of fetal thymocytes in cell suspension for 24 h showed that, whereas immature TCRlowHSAhigh V gamma 3 cells remained viable, all mature TCRhighHSAlow V gamma 3 cells died. These cells died by apoptosis since protein synthesis was required and flow cytometric analysis as well as DNA gel electrophoresis showed that the DNA was degraded to oligonucleosomal bands. Addition of IL-2, IL-4 or IL-7 to suspension cultures of fetal thymocytes rescued V gamma 3 cells from dying. Addition of IL-1, IL-3, IL-5, IL-6, IL-9, TNF-alpha or IFN-gamma was without effect. Phenotypic analysis showed that the alpha-chain of the IL-2 receptor (IL-2R alpha) was expressed by part of the immature V gamma 3 thymocytes, all mature V gamma 3 cells expressed the beta-chain of the IL-2 receptor (IL-2R beta). Addition of anti-IL-2R beta mAb to fetal thymic organ culture (FTOC) resulted in a moderate reduction of the cell number of mature V gamma 3 thymocytes. Addition of anti-IL-2R alpha, anti-IL-4 or anti-IL-7 mAb had no effect. The cell number of mature V gamma 3 cells was highly reduced when both anti-IL-2R beta and anti-IL-7 mAb were added to FTOC.(ABSTRACT TRUNCATED AT 250 WORDS)