Long-wavelength native-SAD phasing: opportunities and challenges

Native single-wavelength anomalous dispersion (SAD) is an attractive experimental phasing technique as it exploits weak anomalous signals from intrinsic light scatterers (Z < 20). The anomalous signal of sulfur in particular, is enhanced at long wavelengths, however the absorption of diffracted X-rays owing to the crystal, the sample support and air affects the recorded intensities. Thereby, the optimal measurable anomalous signals primarily depend on the counterplay of the absorption and the anomalous scattering factor at a given X-ray wavelength. Here, the benefit of using a wavelength of 2.7 over 1.9 Å is demonstrated for native-SAD phasing on a 266 kDa multiprotein-ligand tubulin complex (T₂R-TTL) and is applied in the structure determination of an 86 kDa helicase Sen1 protein at beamline BL-1A of the KEK Photon Factory, Japan. Furthermore, X-ray absorption at long wavelengths was controlled by shaping a lysozyme crystal into spheres of defined thicknesses using a deep-UV laser, and a systematic comparison between wavelengths of 2.7 and 3.3 Å is reported for native SAD. The potential of laser-shaping technology and other challenges for an optimized native-SAD experiment at wavelengths >3 Å are discussed.

Cohort study of pain symptoms and management following impacted mandibular third molar extraction

OBJECTIVE

The aim of this study was to investigate the possibility of intravenous sedation as a useful pain-relieving option for impacted third molar extractions.

SUBJECTS AND METHODS

A prospective cohort study was conducted among patients who underwent bilateral mandibular third molar extractions under local anaesthesia and intravenous sedation (sedation group) and patients who underwent unilateral mandibular third molar extraction under local anaesthesia alone (local anaesthesia group). The frequency of use of postoperative oral analgesia and the intensity of pain assessed using the full cup test were compared between the two groups.

RESULTS

The maximum pain intensity (0-100) on postoperative day 1 in the sedation and local anaesthesia groups was 72.8 ± 16.98 and 84.8 ± 15.84, respectively, and the mean pain intensity was 42.2 ± 16.00 and 49.6 ± 18.94. The maximum and mean pain intensities in the sedation group were significantly milder than those in the local anaesthesia group. The number of oral analgesic doses in the sedation group was significantly smaller on the day of surgery and on postoperative day 1 than in the local anaesthesia group.

CONCLUSIONS

The results of this study suggest that bilateral impacted mandibular third molar extractions under intravenous sedation could be a recommended treatment option.

Deficiency of a STE20/PAK family kinase LOK leads to the acceleration of LFA-1 clustering and cell adhesion of activated lymphocytes

Lymphocyte-oriented kinase (LOK) is a member of the STE20/p21-activated kinase (PAK) family and expressed predominantly in lymphoid organs. Generation of LOK-deficient mice revealed that the leukocyte-function-associated antigen (LFA-1)/intercellular adhesion molecules (ICAM)-mediated aggregation of mitogen-stimulated T cells was greatly enhanced in the absence of LOK. Though levels of total LFA-1 and ICAMs as well as the active form of LFA-1 on T cell blasts were comparable in the presence and absence of LOK, clustering of active LFA-1 detected by binding of soluble ICAM-1 was accelerated in the absence of LOK. These results suggest that LOK is potentially involved in the regulation of LFA-1-mediated lymphocyte adhesion.

[Ameloblastic fibrosarcoma: an immunohistochemical and ultrastructural study of the mesenchymal component]

To study the characteristics of the mesenchymal cells of ameloblastic fibrosarcoma (AFS), three cases of AFS were studied immunohistochemically and ultrastructurally. The results showed that the mesenchymal component of AFS consisted predominantly of fibroblastic cells with a small number of undifferentiated cells, a few histiocytes and occasionally myofibroblastic cells under electron microscope. The fibroblastic cells were Vimentin positive only, and myofibroblastic cells were positive for Vimentin, HHF35 and alpha-SMA. The histiocytes were positive both for kp1 and PG-M1, suggesting that these cells were infiltrating cells from peripheral blood rather than histiocytic differentiation of tumor cells. Compared with ameloblastic fibroma, AFS showed much higher PCNA labeling index, suggesting higher proliferation activity of AFS.

Development of a cell-free binding assay for rat ICAM-1/LFA-1 interactions using a novel anti-rat LFA-1 monoclonal antibody and comparison with a cell-based assay

The importance of the interaction between lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) in the progression of inflammatory responses in vivo has been demonstrated mainly in rats. The present study was undertaken to develop binding assays suitable for measuring the rat ICAM-1/LFA-1 interaction in vitro. We first examined binding of rat T lymphoma FTL43 cells, which express LFA-1, to immobilized rat ICAM-1. Although FTL43 cells bound avidly to immobilized ICAM-1 and the binding was abolished with anti-LFA-1 monoclonal antibodies (mAbs), the binding was not completely inhibited by most anti-ICAM-1 mAbs. We next purified rat LFA-1 from FTL43 cells and constructed a cell-free binding assay. By using a newly developed anti-rat LFA-1 mAb RL14/9, which does not inhibit ICAM-1/LFA-1 interactions, binding of purified rat LFA-1 to immobilized ICAM-1 was successfully detected, whereas only a low signal to noise ratio was observed when binding of ICAM-1 to immobilized LFA-1 was examined. Moreover, we found that simultaneous addition of purified LFA-1 and biotinylated RL14/9 to ICAM-1-coated wells resulted in more sensitive detection of rat ICAM-1/LFA-1 binding. The binding was completely blocked with both anti-LFA-1 and anti-ICAM-1 mAbs and was much more sensitive to inhibition by the ICAM-1-IgG chimera, as compared with the cell-based assay. These results indicate that the cell-free binding assay provides a rapid and sensitive method for screening rat ICAM-1/LFA-1 antagonists, whose therapeutic effect on inflammatory diseases can further be evaluated in vivo.

Affinity and kinetic analysis of the molecular interaction of ICAM-1 and leukocyte function-associated antigen-1

LFA-1 is a member of the beta2 integrin family, and interacts with ICAM-1, a member of the Ig superfamily containing five Ig-like domains. Interaction of LFA-1 with ICAM-1 is important in a number of cellular events, including Ag-specific T cell activation and leukocyte transendothelial migration, which are known to be typically transient and highly regulated. In this study, we have used surface plasmon resonance technology to study the ICAM-1/LFA-1 interaction at the molecular level. A soluble form of LFA-1 (sLFA-1), normally expressed as two noncovalently associated membrane-bound subunits, has been produced, and its interaction with ICAM-1 has been examined. The kinetic analysis of a monomeric sLFA-1 binding to the first two domains of ICAM-1 expressed as a chimeric IgG fusion protein (D1D2-IgG) revealed that sLFA-1 was bound to the D1D2-IgG chimera with a Kd of 500 nM and dissociated with a k(diss) of 0.1 s(-1). Monomeric membrane-bound LFA-1 purified from plasma membranes showed a similar kinetic to sLFA-1. These results suggest that the monovalent interaction between ICAM-1 and LFA-1 has a primarily high affinity and a slow dissociation rate constant as compared with other adhesion molecules, suggesting a potential mechanism for firm adhesion.

RP58 associates with condensed chromatin and mediates a sequence-specific transcriptional repression

An approximately 120-amino acid domain present generally at the NH2 termini, termed the POZ domain, is highly conserved in various proteins with zinc finger DNA binding motifs. We have isolated a novel protein sharing homology with the POZ domain of a number of zinc finger proteins, including the human BCL-6 protein. By using a binding site selection technique (CAST), a high affinity binding site of the protein was determined to be (A/C)ACATCTG(G/T)(A/C), containing the E box core sequence motif. The protein was shown to repress transcription from a promoter linked to its target sequences and was hence named RP58 (Repressor Protein with a predicted molecular mass of 58 kDa). Immunogold electron microscopic study revealed that almost all RP58 is localized in condensed chromatin regions. These observations demonstrate for the first time that a protein mediating a sequence-specific transcriptional repression associates with highly condensed chromatin. We suggest that RP58 may be involved in a molecular link between sequence-specific transcriptional repression and the organization of chromosomes in the nucleus.

Inhibition of human immunodeficiency virus type 1 replication and cytokine production by fluoroquinoline derivatives

We have recently identified 8-difluoromethoxy-1-ethyl-6-fluoro-1, 4-dihydro-7-[4-(2-methoxyphenyl)-1-piperazinyl]-4-oxoquinoline-3-carb oxylic acid (K-12) as a potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) transcription. In the search for more effective derivatives and their mode of action, we have found 7-(3,4-dehydro-4-phenyl-1-piperidinyl)-1, 4-dihydro-6-fluoro-1-methyl-8-trifluoromethyl-4-oxoquinoline-3- carboxylic acid (K-37) and 8-difluoromethoxy-1,4-dihydro-6-fluoro-7-(3, 4-dehydro-4-phenyl-1-piperidinyl)1-[4,(1,2, 4-triazol-1-yl)methylphenyl]-4-oxoquinoline-3-carboxylic acid (K-38) to be more potent inhibitors of HIV-1 replication than K-12. The EC50 values of K-37 and K-38 for HIV-1IIIB were 27 and 3.8 nM in peripheral blood mononuclear cells, respectively. These values were approximately 3- and 24-fold lower than the EC50 of K-12. K-38 was also a more potent inhibitor of HIV-1 replication in chronically infected cells, such as tumor necrosis factor alpha-stimulated OM-10. 1 cells. K-37 and K-38 proved to be more cytotoxic than K-12 for a variety of cell lines as well as peripheral blood mononuclear cells. These compounds were more inhibitory of Tat-induced HIV-1 long terminal repeat-driven gene expression than K-12, which suggests that their mechanism of action is attributable in part to the inhibition of Tat function. Interestingly, K-37 and K-38 could suppress the production of tumor necrosis factor alpha and interleukin 6 in phytohemagglutinin-stimulated peripheral blood mononuclear cells and the expression of intercellular adhesion molecule 1 in tumor necrosis factor alpha-stimulated human umbilical vein endothelial cells at their nontoxic concentrations. In contrast, another K-12 derivative, 1, 4-dihydro-8-dimethylaminomethyl-6-fluoro-7-[4-(2-methoxyphenyl)-1-pip eradinyl]-1-methyl-4-oxoquinoline-3-carboxylic acid (K-42), had anti-HIV-1 activity and cytotoxicity profiles similar to those of K-12, but K-42 scarcely inhibited the cytokine production and intercellular adhesion molecule 1 expression.

Abrogation of bronchial eosinophilic inflammation and airway hyperreactivity in signal transducers and activators of transcription (STAT)6-deficient mice

Signal transducers and activators of transcription 6 (STAT6) is essential for interleukin 4-mediated responses, including class switching to IgE and induction of type 2 T helper cells. To investigate the role of STAT6 in allergic asthma in vivo, we developed a murine model of allergen-induced airway inflammation. Repeated exposure of actively immunized C57BL/6 mice to ovalbumin (OVA) aerosol increased the level of serum IgE, the number of eosinophils in bronchoalveolar lavage (BAL) fluid, and airway reactivity. Histological analysis revealed peribronchial inflammation with pulmonary eosinophilia in OVA-treated mice. In STAT6-deficient (STAT6-/-) C57BL/6 mice treated in the same fashion, there were no eosinophilia in BAL and significantly less peribronchial inflammation than in wild-type mice. Moreover STAT6-/- mice had much less airway reactivity than wild-type mice. These findings suggest that STAT6 plays a crucial role in the pathogenesis of allergen-induced airway inflammation.

Expression of a soluble form of LFA-1 and demonstration of its binding activity with ICAM-1

The interaction between lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) is of importance in a number of cellular events, including antigen-specific T cell activation and emigration of leukocytes into sites of inflammation. We describe here the first use of a recombinant soluble form of human LFA-1 (sLFA-1) for the measurement of the binding between LFA-1 and ICAM-1. sLFA-1 has been successfully expressed and purified. The expressed sLFA-1 was shown to be functionally active by their binding to ICAM-1. Binding of sLFA-1 to ICAM-1 was observed by receptor binding assay. Both monomeric (soluble ICAM-1 or the first two domains of ICAM-1) and dimeric ICAM-1 (IgG chimera of each ICAM-1 fragment) showed inhibitory activity on assay with IC50 values of 400 nM and 40 nM, respectively. These results suggest that the soluble constructs would be useful tools for molecular analysis of ICAM-1/LFA-1 interaction as well as in screening for ICAM-1/LFA-1 antagonists.

Constitutive expression of ICAM-1 in rat microvascular systems analyzed by laser confocal microscopy

The present study aimed to demonstrate constitutive expression of the intercellular adhesion molecule (ICAM)-1 among arterioles, capillaries, and venules in the mesentery and liver and to examine the interaction between cultured endothelial cells and leukocytes in rats. ICAM-1 expression in the microvessels in vivo was visually demonstrated by laser confocal fluorescence microscopy. A monoclonal antibody against rat ICAM-1 (1A29) was labeled with fluorescein isothiocyanate, and the binding ratio between the fluorescence and immunoglobulin was determined for data calibration. Intravascularly administered fluorescein isothiocyanate-labeled 1A29 was distributed heterogeneously among the hierarchy of microvessels in the mesentery: postcapillary venules were the major portion expressing ICAM-1 constitutively, and the density of 1A29 bound to their endothelium was at least 10 times higher than that in true capillaries and arterioles in the same mesentery. On the other hand, the liver expressed ICAM-1 abundantly in sinusoids to the extent similar to that in central venules. These results suggest that postcapillary venules serve as an active gateway with the readiness to help adhere circulating leukocytes exposed to proinflammatory stimuli in acute inflammation.

[A new strategy for treating small cell lung cancer]

Recent results from molecular biology have shown that lung cancer is characterized by multiple, sequentially appearing molecular changes that include genetic and epigenetic alterations. Among all types of lung cancer, small cell lung cancer (SCLC) is associated with the lowest rate of 5-year survival. In this symposium, we introduce our findings regarding the c-kit oncogenes in SCLC. We found that the c-kit gene is strongly expressed in SCLC. The c-kit gene was not expressed in normal bronchial epithelial cells, which indicates that this gene is abberantly transcribed in SCLC. In addition, c-kit-positive cases of SCLC showed autophosphorylation in response to recombinant human stem cell factor. Furthermore, adding rh stem cell factor of SCLC cell lines induced a significant chemotactic response and moderate in vitro cell growth. These results strongly suggest that abnormal expression of the c-kit gene may be involved in the pathogenesis of SCLC by autocrine/paracrine stimulation via the c-kit/SCF signal pathway. To overcome drug resistance, we assessed the efficacy of a chimeric toxin targeted to c-kit receptors.

The effect of anti-adhesion molecule antibody on the development of collagen-induced arthritis

In order to study how inflammatory cells including autoimmune lymphocytes interact with each other to develop collagen-induced arthritis (CIA), we injected monoclonal antibodies against mouse LFA-1 and ICAM-1 into DBA/1 mice immunized with type II collagen (CII). Both antibodies suppressed the development of CIA. These antibodies showed no effect on anti-CII antibody response, although they both significantly suppressed DTH response. It was suggested that anti-adhesion molecule antibodies suppress CIA mainly through their effect on cell-mediated immunity, without affecting humoral immunity under the conditions used.

Sequence and expression of rat ICAM-1

We have isolated cDNA clones-coding for rat intercellular adhesion molecule-1 (RICAM-1) from a cDNA library constructed from rat Ax cells stimulated with IL-1 beta using the mouse ICAM-1 cDNA as a hybridization probe. The RICAM-1 sequence shows 79.1% homology with mouse ICAM-1 and 55.6% homology with human ICAM-1 at the nucleic acid level. In order to examine the expression of RICAM-1 on Chinese hamster ovary (CHO) cells, we constructed the vector, pSV-RICAM1-neo, containing the SV40 promoter. Flowcytometric analysis showed that CHO-K1 cells transfected with pSV-RICAM1-neo expressed high amounts of RICAM-1 on their surfaces.

Timing of immunosuppression in the natural history of autoimmune diseases

We have insufficient data to guide us to the optimal timing of immunosuppression in the natural history of any autoimmune disease. Moreover, there are differences among the many autoimmune diseases and the many drugs available for use. Nevertheless, certain principles have emerged. Prophylactic non-specific immunosuppression prior to the onset of the immune-mediated process often is of minimal benefit. Vigorous immunosuppression shortly after the onset of the immune-mediated process is most effective; many agents are of benefit at such times. If the disease has progressed to substantial clinical involvement, certain drugs previously useful may no longer be effective. At such a time of moderately advanced clinical involvement, only selected agents may suppress the disease. With substantial loss of function of irreplaceable organs, or parts thereof, immunosuppression becomes progressively less effective. Such drugs can interfere with inflammatory processes, but are of little benefit after deletion of cells or scarring of an organ. Therefore, to have any benefit, immunosuppression must be instituted prior to the time of irreversible loss of critical organs or parts thereof.

ICAM-1-dependent pathway is critically involved in the pathogenesis of adjuvant arthritis in rats

Intercellular adhesion molecule 1 (ICAM-1) plays important roles in immune responses. In order to examine whether ICAM-1 is involved in pathogenesis of adjuvant arthritis (AA), we investigated the effect of anti-ICAM-1 mAb, 1A29, on AA in rats. In vivo administration of 1A29 exerted a very strong suppressive effect on the development of arthritis and induced a marked reduction of inflammatory parameters. 1A29 suppressed the Ag-specific proliferative response of lymph node cells from AA rats, suggesting that the mAb blocked the Ag recognition phase. The study using adoptive transfer of AA revealed that 1A29 completely inhibited production of arthritogenic lymphocytes in donors and partially suppressed progression of arthritis in recipients caused by these lymphocytes. These findings indicated that the inhibitory effect of 1A29 on development of arthritis was at least twofold, i.e., 1) interference with cell-cell interaction between APC and T cells, which resulted in abrogation of effector cell generation; and 2) blocking of effector cell migration to inflammatory lesions. These results indicated that ICAM-1-dependent pathway is critically involved in the pathogenesis of AA. The data support the concept that ICAM-1-dependent pathways are important in chronic inflammatory disease.

ICAM-1-dependent pathway is critically involved in the pathogenesis of adjuvant arthritis in rats

Intercellular adhesion molecule 1 (ICAM-1) plays important roles in immune responses. In order to examine whether ICAM-1 is involved in pathogenesis of adjuvant arthritis (AA), we investigated the effect of anti-ICAM-1 mAb, 1A29, on AA in rats. In vivo administration of 1A29 exerted a very strong suppressive effect on the development of arthritis and induced a marked reduction of inflammatory parameters. 1A29 suppressed the Ag-specific proliferative response of lymph node cells from AA rats, suggesting that the mAb blocked the Ag recognition phase. The study using adoptive transfer of AA revealed that 1A29 completely inhibited production of arthritogenic lymphocytes in donors and partially suppressed progression of arthritis in recipients caused by these lymphocytes. These findings indicated that the inhibitory effect of 1A29 on development of arthritis was at least twofold, i.e., 1) interference with cell-cell interaction between APC and T cells, which resulted in abrogation of effector cell generation; and 2) blocking of effector cell migration to inflammatory lesions. These results indicated that ICAM-1-dependent pathway is critically involved in the pathogenesis of AA. The data support the concept that ICAM-1-dependent pathways are important in chronic inflammatory disease.

Interleukin 1-induced maturation of progenitor thymocytes

Regulation of thymocyte development was assessed by culturing purified CD4-CD8- thymocytes with cytokines. Sorted CD3-CD4-CD8- adult thymocytes responded to the combination of interleukin (IL) 1 plus IL 2 without additional mitogens or co-mitogens with both cellular proliferation and cell surface expression of the T cell receptor (TcR)/CD3 complex. IL2 alone induced neither proliferation nor cell surface TcR/CD3 expression. IL1 alone was sufficient to induce cell surface TcR/CD3 without proliferation. Prior to stimulation with cytokines, the progenitor CD4-CD8- thymocytes accumulated TcR beta and CD3 gamma, delta, epsilon and zeta mRNA but TcR alpha mRNA was not detectable. Stimulation with IL 1 led to a dramatic induction of TcR alpha mRNA without an increase in the other transcripts. These studies suggest that IL 1 regulates the differentiation status of immature adult thymocytes. Nuclear run-on studies suggested that the increase in TcR alpha mRNA accumulation induced by cytokines might result from post-transcriptional accumulation.

Responsiveness of fetal and adult CD4-, CD8- thymocytes to T cell activation

Day-14 fetal CD4-, CD8- thymocytes showed a greater proliferative response to PMA + IL-4 than did adult double-negative thymocytes. In contrast, adult double-negative thymocytes were more responsive to PMA + IL-1 + IL-2 or to IL-1 + IL-2 alone. The adult double-negative thymocytes showed significantly greater proliferation than fetal thymocytes after stimulation via anti-CD3 or anti-Thy-1 in the presence or absence of interleukins (IL-1 + IL-2 or IL-4). Adult CD4-, CD8- thymocytes also exhibited greater calcium mobilization following anti-CD3 stimulation IL-2-dependent activation with anti-Thy-1 or IL-1 + IL-2 in the absence of PMA resulted in marked expansion of CD 3+, F23.1+, CD4-, CD8- thymocytes, a population absent in fetal thymocytes but constituting 4% of pre-cultured CD4-, CD8- adult thymocytes. IL-4 + PMA failed to expand this CD 3+ population. It is hypothesized that before expression of functional TCR, T cell development may be more dependent on activation pathways not using IL-2; after TCR expression, IL-2-dependent pathways, including Thy-1-mediated stimulation, become functional.

Responsiveness of fetal and adult CD4-, CD8- thymocytes to T cell activation

Day-14 fetal CD4-, CD8- thymocytes showed a greater proliferative response to PMA + IL-4 than did adult double-negative thymocytes. In contrast, adult double-negative thymocytes were more responsive to PMA + IL-1 + IL-2 or to IL-1 + IL-2 alone. The adult double-negative thymocytes showed significantly greater proliferation than fetal thymocytes after stimulation via anti-CD3 or anti-Thy-1 in the presence or absence of interleukins (IL-1 + IL-2 or IL-4). Adult CD4-, CD8- thymocytes also exhibited greater calcium mobilization following anti-CD3 stimulation IL-2-dependent activation with anti-Thy-1 or IL-1 + IL-2 in the absence of PMA resulted in marked expansion of CD 3+, F23.1+, CD4-, CD8- thymocytes, a population absent in fetal thymocytes but constituting 4% of pre-cultured CD4-, CD8- adult thymocytes. IL-4 + PMA failed to expand this CD 3+ population. It is hypothesized that before expression of functional TCR, T cell development may be more dependent on activation pathways not using IL-2; after TCR expression, IL-2-dependent pathways, including Thy-1-mediated stimulation, become functional.

Activation of CD 4-, CD 8- thymocytes with IL 4 vs IL 1 + IL 2

Thymocytes from C57BL/6 mice were highly purified to obtain the CD 4-, CD 8- subpopulation which constitutes only 5% of all thymocytes. Substantial proliferation was induced in vitro with either IL-1 + IL-2 or with IL-4 in the presence of PMA. IL-1 and IL-2 synergized in inducing proliferation of these purified CD 4-, CD 8- thymocytes whereas neither synergized with IL-4. In order to determine whether stimulation with IL-1 + IL-2 acted via IL-4 or vice versa, cultures were treated reciprocally with affinity-purified anti-IL-2 or anti-IL-4 antibodies. Cultures with IL-4 were inhibited by anti-IL-4 but were unaffected by anti-IL-2. The CD 4-, CD 8- thymocytes cultured with IL-1 + IL-2 + anti-IL-2 were inhibited to baseline IL-1 stimulation. At low concentrations of IL-1 (1 U/ml) and IL-2 (100 U/ml), anti-IL-4 had no effect, whereas at higher levels of IL-1 (2 U/ml IL-1), and 100 or 200 U/ml IL-2, anti-IL-4 significantly reduced DNA synthesis. This result suggests that at higher concentrations the combination of IL-1 + IL-2 can induce cells to produce IL-4 which then contributes to overall proliferation. When CD 4-, CD 8- thymocytes were cultured with the low doses of IL-1 + IL-2 for 72 h, 62% expressed cell surface T3 complex (vs 11% at initiation) and 27% were F23.1+ (vs 5% at initiation). In contrast, culture with IL-4 led to no increase in numbers of T3+ cells and none were F23.1+; however, there was coexpression of Thy1 and 6B2 on 20% of cells at the end of culture (vs 4% at initiation). Thus, IL-1 + IL-2 causes expansion of a CD 4-, CD 8- thymocyte population expressing the alpha, beta-T cell receptor, whereas IL-4 induces cells to express a phenotype present in small numbers in the periphery of normal mice and in larger numbers in mice bearing the lpr gene.

Activation of CD 4-, CD 8- thymocytes with IL 4 vs IL 1 + IL 2

Thymocytes from C57BL/6 mice were highly purified to obtain the CD 4-, CD 8- subpopulation which constitutes only 5% of all thymocytes. Substantial proliferation was induced in vitro with either IL-1 + IL-2 or with IL-4 in the presence of PMA. IL-1 and IL-2 synergized in inducing proliferation of these purified CD 4-, CD 8- thymocytes whereas neither synergized with IL-4. In order to determine whether stimulation with IL-1 + IL-2 acted via IL-4 or vice versa, cultures were treated reciprocally with affinity-purified anti-IL-2 or anti-IL-4 antibodies. Cultures with IL-4 were inhibited by anti-IL-4 but were unaffected by anti-IL-2. The CD 4-, CD 8- thymocytes cultured with IL-1 + IL-2 + anti-IL-2 were inhibited to baseline IL-1 stimulation. At low concentrations of IL-1 (1 U/ml) and IL-2 (100 U/ml), anti-IL-4 had no effect, whereas at higher levels of IL-1 (2 U/ml IL-1), and 100 or 200 U/ml IL-2, anti-IL-4 significantly reduced DNA synthesis. This result suggests that at higher concentrations the combination of IL-1 + IL-2 can induce cells to produce IL-4 which then contributes to overall proliferation. When CD 4-, CD 8- thymocytes were cultured with the low doses of IL-1 + IL-2 for 72 h, 62% expressed cell surface T3 complex (vs 11% at initiation) and 27% were F23.1+ (vs 5% at initiation). In contrast, culture with IL-4 led to no increase in numbers of T3+ cells and none were F23.1+; however, there was coexpression of Thy1 and 6B2 on 20% of cells at the end of culture (vs 4% at initiation). Thus, IL-1 + IL-2 causes expansion of a CD 4-, CD 8- thymocyte population expressing the alpha, beta-T cell receptor, whereas IL-4 induces cells to express a phenotype present in small numbers in the periphery of normal mice and in larger numbers in mice bearing the lpr gene.

Production of colony-stimulating factor from macrophages by muroctasin

The effect of a muramyl dipeptide analog, N2-[(N-acetylmuramoyl)-L-alanyl-D-isoglutamyl]-N6-stearoyl-L-lysin e (MDP-Lys(L18), muroctasin), on the colony-stimulating factor (CSF) production was investigated in vitro. MDP-Lys(L18) stimulated murine peritoneal macrophages to induce CSF. However, the compound produced more CSF in the presence of both macrophages and T cell enriched fraction than in the absence of T cells. This phenomenon was found to be attributed to the fact that MDP-Lys(L18) also stimulated macrophages to induce interleukin 1 (IL-1) and the IL-1 induced CSF production by T cells. These findings suggest that macrophages may be the first target cells of MDP-Lys(L18) to produce CSF.

Augmentation of immune responses by a muramyl dipeptide analog, MDP-Lys(L18)

The effects of N2-(N-acetyl-muramyl-L-alanyl-D-isoglutamyl)-N6-stearoyl-L-lysine (MDP-Lys(L18], a muramyl dipeptide (MDP) analog, on the immune responses in mice were studied. MDP-Lys(L18) augmented the mitogenic responses of splenic lymphocytes to phytohemagglutinin (PHA) and lipopolysaccharide (LPS) at 0.1-10 micrograms/ml, and antibody formation to sheep red blood cell (SRBC) in normal and immunosuppressed mice, and to dinitrophenyl (DNP)-Ficoll. In addition, MDP-Lys(L18) potentiated polyclonal B cell activation both in vivo and in vitro. It was also found that MDP-Lys(L18) augmented the cellular immune responses, such as mixed lymphocyte reaction (MLR) and delayed type hypersensitivity (DTH). These effects of MDP-Lys(L18) were more potent than those of MDP. These findings may be attributed to the interleukin 1 (IL-1)-inducing activity of MDP-Lys(L18).

FT-2 antigen for distinguishing lymphocyte subpopulations in the developing thymus

The surface phenotypes of lymphoid cells in the developing embryonic thymus were characterized by using monoclonal antibodies. FT-2 antigen thus defined was predominantly expressed on thymocytes in the earlier embryonic stages in all the inbred mouse strains tested. The immunofluorescence and immunoperoxidase tests indicated that, like FT-1 antigen, the proportion of FT-2+ fetal thymocytes rapidly decreased with increase in gestation time, and these cells disappeared by day 19 of gestation. The treatment of fetal thymocytes with anti-FT-1 plus complement eliminated not only FT-1+, but also FT-2+ cells, whereas the treatment with anti-FT-2 failed to eliminate approximately 40% of FT-1+ cells, suggesting that embryonic thymocytes can be provisionally divided into at least three subpopulations, FT-1+2+, FT-1+2- and FT-1-2-.

A new differentiation antigen (FT-1) shared with fetal thymocytes and leukemic cells in the mouse

A mouse monoclonal antibody (IgM) was obtained by cell hybridization between X63-Ag8.653 myeloma cells and spleen cells from a BALB mouse that was immunized with GRSL leukemia cells of the GR strain. This antibody identified a unique fetal antigen, which is expressed exclusively on embryonic thymocytes of all strains tested. Therefore, the antigen defined was named fetal thymus antigen-1, FT-1. The proportion of FT-1+ fetal thymocytes detected by immunofluorescence assay sharply decreases as gestation time increases, and finally they disappear from the thymus. On the other hand, Thy-1+ cells increase in inverse proportion. The immunofluorescence studies and absorption tests showed that FT-1 antigen is not detectable on brain, liver, kidney, or lymphoid tissue cells of adult mice. However, it is expressed on some leukemia cells of various mouse strains, which demonstrated that this is the first example of an oncofetal antigen of a mouse leukemia. The molecular weight of FT-1 antigen on leukemia cells was estimated to be 130,000 by means of biosynthetic labeling with [3H]galactose and [35S]methionine. The two-dimensional gel electrophoresis pattern of FT-1 antigen shows a family of glycoproteins with extensive charge heterogeneity. It was also shown that the FT-1 antigen molecule carries the receptor for DBA lectin.

Immunopotentiation by a new antitumor polysaccharide, DMG, a degraded D-manno-D-glucan from Microellobosporia grisea culture fluid

The immunopharmacological behavior of DMG, an antitumor polysaccharide, was studied in mice. DMG administered ip or sc stimulated peritoneal macrophages to produce high levels of interleukin-1 activity, which can amplify successive immune responses. DMG dose-dependently and schedule-dependently increased the cellular immune response against allogeneic tumor cells and the humoral immune response to sheep erythrocytes. DMG also enhanced nonspecific antitumor effector functions, such as natural killer activity of spleen and peritoneal cells, and the cytostatic activity of peritoneal macrophages. Peritoneal macrophages activated by ip or sc injection of DMG exhibited high cytostatic activity, especially after exposure in vitro to lymphokine supernatants containing macrophage activation factor. Moreover, granulocyte/macrophage colony-stimulating activity in the serum increased 2-10 hr after DMG administration. Thus, DMG potentiated antigen-specific immunological functions and nonspecific functions of host defense systems against cancer both qualitatively and quantitatively.

Combination therapy of murine tumors with a degraded D-manno-D-glucan (DMG) from Microellobosporia grisea, and cyclophosphamide

DMG, a degraded D-manno-D-glucan with a host-mediated antitumor activity did not significantly enhance nor inhibit the development of suppressor cells for either the antibody-forming response or the delayed hypersensitivity reaction to sheep red blood cells. Cyclophosphamide (CY), which inhibited the generation of suppressor cells, was combined with DMG in treatment of murine syngeneic tumors to obtain a higher antitumor activity. The antitumor activity of the combination against MH134 hepatoma was synergistically higher than that of either component alone. A marked antitumor effect of the combination treatment against MM46 mammary carcinoma was also shown. High levels of antitumor delayed hypersensitivity reactions were observed with this combination therapy. The possible roles of DMG and CY in this combination therapy are discussed.

Immune reactions of liposomes containing cardiolipin and their relation to membrane fluidity

The relation between the immune reactions of phosphatidylcholine liposomes containing cardiolipin with or without cholesterol and the physical state of the liposomes was studied. In egg yolk phosphatidylcholine liposomes, both immune agglutination and complementmediated immune damage occurred irrespective of the presence of cholesterol. Immune agglutination also occurred at all temperatures tested (0--40 degrees C). On the other hand, in dipalmitoylphosphatidylcholine liposomes, both reactions depended on the cholesterol content, but immune agglutination occurred even in the absence of cholesterol above the phase transition temperature at which liposomal membranes became fluid. The finding of antibodies to liposomes was found to be independent of the physical state of the liposomal membranes. The requirement of the fluid state of liposomal membranes for immune reactions is discussed.