CD40L-null NKT cells provide B cell help for specific antibody responses

CD1d-binding glycolipids exert potent adjuvant effects on T-dependent Ab responses. The mechanisms include cognate interaction between CD1d-expressing B cells and TCR-expressing Type I CD1d-restricted natural killer T cells (NKTs). However, the critical NKT-derived factors that stimulate B cells are poorly understood. We tested the hypothesis that CD1d-driven CD40L expression by NKT cells influences humoral immunity. Bone marrow chimeras with CD40L(+/+) or CD40L(-/-) NKT cells were immunized with Ag plus CD1d ligand before measuring Ab responses. CD40L(-/-) NKT cells stimulated higher endpoint Ab titers than controls expressing CD40L. In contrast, immunization of CD40L(-/-) mice revealed that CD40L(-/-) NKT cells could not provide B cell help when Th cells lacked CD40L. We report that CD40L(-/-) NKT cells can provide help for Ab production and do so cooperatively with CD40L(+/+) Th cells. We suggest that the manner in which NKT cells provide B cell help is distinct from that of Th cells.

Anaplastic large cell lymphomas: a study of 75 pediatric patients

In this article, we describe the morphologic and immunophenotypic features of 75 cases of pediatric anaplastic large cell lymphoma (ALCL). According to the World Health Organization classification, 49 cases were common subtype ALCL, and respectively, 3, 6, and 17 cases were small cell, lymphohistiocytic, or mixed histologic variants. Anaplastic lymphoma kinase positivity was detected in 90.7% of the tumors and, using a panel of 9 T-cell surface markers, 88% could be assigned to the T-cell lineage. A molecular analysis for the T-cell receptor gamma (TCR- gamma) and the heavy chain of the immunoglobulin H rearrangements was performed on 6/9 ALCLs with a null immunophenotype, and a TCR clonal pattern was detected in 5/6 cases. In addition, 94.1% were immunoreactive for 1 or more cytotoxic proteins (Tia1, granzyme B, or perforin), and 15% expressed CD56. Clusterin, CD83, and Pax5, respectively, expressed in 91.3%, 1.7%, and 0% of the ALCLs, were useful biomarkers for the differential diagnosis with Hodgkin's lymphomas.

Expansion of IL-3-responsive IL-4-producing non-B non-T cells correlates with anemia and IL-3 production in mice infected with blood-stage Plasmodium chabaudi malaria

A prominent switch of CD4+ T cells from Th1 to Th2 type response occurs in mice infected with the non-lethal malaria parasite Plasmodium chabaudi chabaudi AS around the time of peak parasitemia. This is reflected by a decrease in IFN-gamma- and an increase in IL-4-producing cells. The peak occurs approximately 9-10 days after infection and is accompanied by anemia. The mechanism behind the switch in Th cell response is poorly understood. We here report on the production of IL-4 from a non-T cell source during P. chabaudi infection in BALB/c mice. Flow cytometric analysis of spleen and peripheral blood leukocytes (PBL) showed a dramatic increase in the percentage of non-B non-T (NBNT) cells 9-23 days after P. chabaudi infection with peak values by day 15 (approximately 30 % of splenocytes and approximately 55 % of PBL being NBNT cells). The expansion of NBNT cells correlated closely with the appearance of a cell type secreting IL-4 and IL-6 following stimulation with IL-3 and/or cross-linking of FcgammaR. Compared to cells from uninfected animals, NBNT cells from P. chabaudi-infected mice were shown to be hyper-responsive to IL-3. The levels of the hematopoietic cytokine IL-3 were elevated in supernatants from unstimulated spleen cell cultures as well as in serum at the same time points at which NBNT cell-derived IL-4 and IL-6 were detected from spleen cultures and PBL. Thus, IL-3-responsive IL-4-producing NBNT cells may provide cytokines supporting the switch from Th1 to a Th2 response which is important for the final clearance of the parasite in P. chabaudi malaria.

Analysis of monoclonal antibodies that recognize gamma delta T/null cells

Thirty two monoclonal antibodies (mAbs) from the first round of analysis in the Second International Swine CD Workshop were placed together with additional mAb derived from the first workshop in the null cell panel for further evaluation. Preparations of peripheral blood leukocytes, concanavalin A stimulated peripheral blood mononuclear cells, and spleen cells were used in flow cytometric analyses. Nineteen mAbs identified molecules that were not expressed on null cells, not lineage specific, or recognized activation molecules. Sixteen mAbs including control mAbs were identified that were specific for null cells. One of the latter mAbs, 041 (PGBL22A), that recognizes a determinant on a constant region of porcine gamma delta TcR established the majority of null cells are gamma delta T cells. Use of this mAb in further comparisons demonstrated the gamma delta T cell population is comprised of two major subpopulations, one negative and one positive for CD2. Two color analyses demonstrated that 11 of the mAbs formed a broad cluster that included control mAbs 188 (MAC320) that defined the CD2 negative SWC6 cluster in the first workshop and mAb 122 (CC101) that might recognize an orthologue of bovine WC1 and nine mAbs that recognize determinants on one or more molecules with overlapping patterns of expression on subsets of CD2- gamma delta T cells. Two groups of mAbs formed the previously identified subset clusters SWC4 and SWC5. Two new mAbs formed a third subcluster. Three mAbs did not form clusters. Three mAbs predicted to recognize TcR in the first workshop (020 [PT14A], 021 [PT79A], and 022 [MUC127A]) and mAb PGBL22A were shown to immunoprecipitate a 37, 40 kDa heterodimer.

Molecular analysis of the IgH gene in 212 cases of Hodgkin's disease: correlation of IgH clonality with the histologic and the immunocytochemical features

The aims of this study are to evaluate the frequency of clonal immunoglobulin heavy chain gene rearrangements in paraffin-embedded samples of Hodgkin's disease (HD) with use of the polymerase chain reaction method and to correlate the molecular findings with the histologic and immunocytochemical features. DNA extracts from paraffin-embedded sections from 212 HD samples were used for amplification of the IgH gene by use of framework 2 and framework 3 region primers. Immunohistochemical studies were performed on paraffin sections by use of monoclonal antibodies for CD20 and latent membrane protein-1 and polyclonal antibody for CD3. With use of both primer combinations, monoclonality was detected in 18.7% of lymphocyte-predominant HD cases and in 32.2% of classical HD cases. These results suggest that immunoglobulin heavy chain gene clonal rearrangements are relatively frequent in classical HD. In addition, the statistical analyses of the genotypic and immunocytochemical data revealed that the detection of B-cell populations is significantly associated with the expression of CD20 on HRS cells. There was, however, no correlation between the histologic subtype, the percentage of HRS cells, the presence of latent membrane protein-1 expression, and the molecular analysis results.

The behaviour of monoclonal antibodies in the First International Pig CD Workshop reacting with gamma delta/Null T lymphocytes in the blood of SLAb/b line pigs

Further studies were carried out on the monoclonal antibodies (mAbs) from the First International Swine CD Workshop which react with gamma delta Null T-lymphocytes, defined by the binding of mAb w020/141 (MAC320) as Swine Workshop Cluster number SWC6. Studies were also carried out on several other mAbs from the same workshop which identify other CD antigens, but whose binding is not restricted exclusively to gamma delta Null T-lymphocytes. The first group consists of 11 mAbs (w021, w022, w059-w065, w105 and w117) and the second group of 18 mAbs (w008, w026, w056, w067-w071, w080, w091-w094, w110, w111, w118, w119 and w121). All mAbs were characterised by binding to peripheral blood lymphocytes (PBL) from normal, sham-thymectomized (STx) and thymectomized (Tx) pigs of the Babraham SLAb/b line and by their overlap, using two-colour immunofluorescence with biotinylated mAb MAC320 (w020/141), which identifies all gamma delta Null cell T-lymphocytes and the Null cell subpopulation identified by MAC319 (w021). The Null cell-specific mAbs were also used in inhibition studies of MAC319 and MAC320 binding and by staining PBL with pairs of mAbs together with either MAC319 or MAC320. Based on these data we suggest a putative relationship of the Null cell subsets defined by these mAbs with each other.

Regulation of T cell receptor (TCR)-beta locus allelic exclusion and initiation of TCR-alpha locus rearrangement in immature thymocytes by signaling through the CD3 complex

During thymocyte differentiation, the T cell receptor (TCR)-beta genes are rearranged before the TCR-alpha genes. Immature CD4-8- double-negative thymocytes with a productive rearrangement of the TCR-beta locus are selected to continue maturation to the CD4+8+ double-positive stage, driven by signals through the pre-TCR. The signals through the pre-TCR can be synchronized by injection of mice with anti-CD3 epsilon monoclonal antibody. Using this approach, we demonstrated coordinated induction of a triad of responses in immature thymocytes: arrest of V to DJ rearrangement in the TCR-beta locus, transient down-regulation of rearrangement-activating gene (RAG)-1 and RAG-2 transcripts, and initiation of germ-line transcription of the TCR-alpha locus. These results suggest that the transition from TCR-beta to TCR-alpha locus rearrangement is controlled by signal transduction through the pre-TCR.

T lymphocyte development in p56lck deficient mice: allelic exclusion of the TcR beta locus is incomplete but thymocyte development is not restored by TcR beta or TcR alpha beta transgenes

The protein tyrosine kinase, p56lck, is involved in signal transduction in mature T cells and in the molecular events controlling early thymocyte differentiation. Thymuses of mice deficient for p56lck expression (p56lck-/-) consist of immature CD4-CD8- double-negative (DN) and CD4+CD8+ double-positive (DP) thymocytes and are severely reduced in total cell number. In this report we have studied DN thymocytes from p56lck-/- mice and found an increase in the proportion of the CD44-CD25+ subset, suggesting that transit through this stage, which is known to require T cell receptor (TcR) beta expression, may be delayed in the absence of p56lck expression. In addition, the expression of a transgenic TcR beta chain or TcR alpha beta pair did not restore thymic development in p56lck-/- mice. However, in contrast to mice expressing a dominant negative isoform of p56lck in which DP thymocytes do not develop, DP thymocytes still develop in nontransgenic and TcR transgenic p56lck-/- mice. These results demonstrate that expansion of the DP subset is impaired in p56lck-/- mice. In contrast, allelic exclusion is not severely compromised. Although there was an increase in the number of peripheral T cells expressing more than one V beta chain in TcR transgenic p56lck-/- mice, we found that inhibition of endogenous TcR beta gene rearrangement was almost complete in thymocytes of V beta transgenic p56lck-/- mice and we could not detect any peripheral T cells that expressed more than one V beta chain in non-transgenic p56lck-/- mice.

IgE receptor-positive non-B/non-T cells dominate the production of interleukin 4 and interleukin 6 in immunized mice

The phenotype and antigenic specificity of cells secreting interleukin (IL) 4, IL-6, and interferon gamma was studied in mice during primary and secondary immune responses. T lymphocytes were the major source of interferon gamma, whereas non-B/non-T cells were the dominant source of IL-4 and IL-6 in the spleens of immunized animals. Cytokine-secreting non-B/non-T cells expressed surface receptors for IgE and/or IgG types II/III. Exposing these cells to antigen-specific IgE or IgG in vivo (or in vitro) "armed" them to release IL-4 and IL-6 upon subsequent antigenic challenge. These findings suggest that non-B/non-T cells may represent the "natural immunity" analogue of CD4+ T helper type 2 cells and participate in a positive feedback loop involved in the perpetuation of T helper type 2 cell responses.

Co-infusion of normal bone marrow partially corrects the gld T-cell defect. Evidence for an intrinsic and extrinsic role for Fas ligand

Ipr and gld mice develop systemic autoimmune diseases with nearly indistinguishable manifestations, including the accumulation of massive numbers of CD4-CD8- T lymphocytes. In vivo chimera experiments have shown that the Ipr mutation is functionally expressed in both T and B cells. When lethally irradiated Ipr mice were given a combination of normal and Ipr bone marrow, only Ipr-derived B cells produced autoantibodies and only Ipr-derived T cells hyperproliferated. In contrast, analogous experiments with gld mice showed that the co-infusion of normal bone marrow greatly reduced autoantibody production. These results indicated that the gld B cell defect was extrinsic to those cells producing autoantibodies, in agreement with the recent molecular data showing that the normal gene products of the Ipr and gld loci form an interacting receptor-ligand pair. In the present study, we have extended our functional studies with gld mice using T cell-marked congenic donors. Lymphadenopathy was reduced three- to fourfold in gld mice given a combination of congenic normal and gld bone marrow compared with mice given gld bone marrow alone, and the absolute number of CD4-CD8- T cells was reduced by a factor of 7. Surprisingly, the residual CD4-CD8- T cells present in the mixed chimeras were derived entirely from the gld donor marrow. This suggests that the gld mutation results in both an extrinsic and intrinsic defect in T cells.

Characterization of a functional null cell line derived from NZB x NZW)F1 mice

We attempted to establish a null cell line from NZB x NZW(B/W)F1 mice in order to investigate a regulatory role of null cells during polyclonal B cell activation in autoimmune diseases. NB2.2, a representative subclone of resulting null cell lines, was maintained in long-term tissue culture with 10% mouse ConA supernatant (MCAS). Interestingly, the cell free supernatant of the NB2.2 cells (NB-CFS) showed marked synergistic effects on IgM secretion by B cells induced by IL-5. In addition, NB-CFS had the ability to augment the production of autoantibodies against bromelain-treated mouse red blood cells (BrMRBC) and single-stranded DNA (ssDNA) by B cells induced by IL-5. To determine whether NB2.2 cells induce polyclonal B cell activation and autoantibody generation in vivo, BALB/c mice were injected with NB2.2 cells. The results showed that the level of anti-ssDNA antibodies in sera of BALB/c mice injected with NB2.2 cells was significantly higher than that of control BALB/c mice injected with FDC-P2 cells. In addition, splenic B cells from mice injected with NB2.2 cells significantly proliferated in vitro in response to IL-4 and IL-5, and produced anti-ssDNA antibodies in the presence of IL-5. These results suggest that NB2.2, a null cell line established from B/WF1 mice, produces mediators capable of promoting polyclonal B cell activation and inducing autoantibody secretion, and that this kind of null cell may play an important role in the pathogenesis of autoimmune diseases.

Report on the behaviour of monoclonal antibodies in the First International Pig CD Workshop identifying the Null cell families

Clustering analyses were carried out on data from five independent laboratories testing 22 monoclonal antibodies (mAbs) reacting with CD2-sIg-lymphocytes on 14 pig blood and/or tissue lymphoid target cells using cytofluorometry. This was coupled with extensive further studies on blood lymphocytes from normal and thymectomised SLAb/b inbred pigs. These mAbs formed two groups: those mainly identifying the large blood-borne thymus-dependent Null T cells (N) and those reacting with tissue and a small number of blood-borne thymus-independent lymphocytes (N'). Based on their tissue cell reaction patterns, the 10 N' mAbs formed three main groups: N'1A and B; N'2A and B; and N'3. The 12N mAbs fell into four groups N4-N7; N6 was divided into subgroups A-D. One N' (032) and two N mAbs (010 and 063) were unclustered. Based on these data, swine workshop cluster numbers were designated to groups N5 (021, 022 and 059) as SWC4, N6 (061 and 117) as SWC5 and N7 (020 and 141) as SWC6, the latter exceptionally as a single antibody, MAC320, since it is the 'type' mAb identifying effectively all blood Null T lymphocytes. Future research and workshops will have to define with a wider range of techniques the relationships, molecular properties and functional roles of the several new, perhaps novel, antigens identified by this family of fascinating, as yet still poorly defined, mAbs.

The Null/gamma delta TCR+ T cell family in the pig

The very large population of highly thymus-dependent, non-adherent 'Null' blood lymphocytes in young pigs, which lack most surface markers characteristic of classical T-cell subsets, have recently been shown to bear several novel population- and subset-specific antigens and gamma delta T-cell receptors. These T-lymphocytes differ radically from conventional CD2-positive T-cells in their origins, biological lifespan, tissue distribution, migration behaviour, cell surface phenotype, immunological responsiveness and mechanisms of trafficking through constitutive lymphoid tissues and inflammatory lesions. Elucidation of the roles of these enigmatic cells and their characteristic surface macromolecules in the initiation and regulation of immune functions promises to reveal much of fascination.

Expression of intercellular adhesion molecule-1 and infiltration of lymphocytes in glomeruli of patients with IgA nephropathy

Using immunofluorescence, we studied 19 patients with IgA nephropathy to determine whether the expression of intercellular adhesion molecule (ICAM)-1 in glomeruli might reflect the disease activity. The relationship between the expression of ICAM-1 and the infiltration of lymphocytes, monocytes and polymorphonuclear leukocytes (PMN) in glomeruli of IgA nephropathy cases was examined. The expression of ICAM-1 in patients in the advanced stage was significantly higher than that in patients in the mild stage. In double immunofluorescence, the distribution of ICAM-1 expression in glomeruli was different from that of IgA deposition in patients in both stages. Glomeruli which showed increases of ICAM-1 expression had marked infiltration of lymphocytes (OKT4+, OKT8+ T cells), and monocytes (OKM1+ cells). Increase of urinary protein and decreases in renal function were observed in patients in the advanced stage. It appears that the expression of ICAM-1 is closely linked to glomerular cell proliferation, and infiltration of lymphocytes and monocytes in patients with IgA nephropathy. However, the expression of ICAM-1 in glomeruli might not be correlated with IgA-dominant immune complexes in this disease.

[Autoimmune reactions in diseases of streptococcal etiology]

In this work 98 cases of streptococcal tonsillitis and 361 cases of erysipelas were studied. As revealed in this study, in relapsing forms of streptococcal infection antibodies to cross-reacting antigens of the infective agent appear in the blood. The synthesis of antibodies to the basal layers of skin epithelium was accompanied by an increase in the concentration of medium-size immune complexes, 0-cell population and by a decrease in the number of T suppressors. The mechanism of the development of the autoimmune process in relapsing forms of streptococcal infection is discussed.

Subsets of null and gamma delta T-cell receptor+ T lymphocytes in the blood of young pigs identified by specific monoclonal antibodies

Rat monoclonal antibodies (mAb) against isolated pig Null T cells were derived using a novel two-colour cytofluorometric assay. One (MAC320) identified all blood CD2-sIg- 'Null' cells (present at up to approximately 6 x 10(6)/ml). Another type (MAC319 and MAC318) identified a subset comprising approximately 60% or approximately 30% of the Null cell population. This percentage appears genetically determined. This subset partially overlapped with a gamma delta T-cell receptor+ (TcR+) population which consisted of approximately 40% of Null T cells. The antibodies did not react with other leucocyte or lymphocyte populations. In non-reducing conditions, MAC320 precipitated two molecules at approximately 270,000-280,000 MW in SDS-PAGE; the larger of which was also precipitated by MAC319 (and MAC318, which binds to the same epitope). Under reducing conditions, MAC320 immunoprecipitated two or three polypeptide chains at approximately 130,000-160,000 MW; MAC319 precipitated only the largest of these polypeptides. The large MAC319+ MAC320+ molecule on one subset is removed by bromelain treatment; the smaller MAC319- MAC320+ molecule on the remaining Null cells is not bromelain sensitive. Several properties of this new antigen complex specific to pig Null T cells show that it is distinct from the ruminant T19 complex.

Murine splenic null cell compartment contains distinct haemopoietic subpopulations: enlargement of a myeloid and an undifferentiated subset with the development of splenomegaly in New Zealand black mice

We have previously reported that non-T, non-B 'null' cells increase with age in New Zealand Black (NZB) mice resulting in splenomegaly. Using a panel of monoclonal antibodies recognizing lineage-specific cell surface antigens we demonstrate four distinct subsets within this null cell compartment: (1) undifferentiated; (2) T lineage with undetectable Thy-1.2; (3) myeloid/erythroid; and (4) a pre-B/plasma cell type. All four subsets also occur in non-autoimmune mice. The frequency of these populations are similar in the young mice of all the strains examined, although the total number of null cells is higher in NZB. The elevation of null cells in young NZB mice is controlled by a single dominant gene in the genetic cross with New Zealand White (NZW) mice and does not appear closely related to the subsequent development of autoimmune disease. The proportion of myeloid/erythroid null cells increases with age in NZB as splenomegaly develops.

Changes in the populations of null, NK1.1+, and Thy1lo lymphocytes in the bone marrow of tumor-bearing mice: Effect of indomethacin treatment

Mouse bone marrow produces many "null" lymphocytes which lack B and T lineage markers (B220-Thy1-). A subset of these cells expresses the natural killer (NK) cell marker, NK1.1. In addition, some rapidly renewed bone marrow lymphocytes express low intensities of Thy1 (Thy1lo). In view of their possible implication in tumor-host interactions these various cell populations have now been examined in mice injected with either the nonmetastatic Ehrlich ascites (EA) tumor or the Lewis lung carcinoma (LLc), a highly metastatic solid tumor. In each case, the number of null lymphocytes, as defined by a lack of radioautographic labeling of either B220 glycoprotein or Thy1, increased markedly in both the bone marrow and spleen. Treatment with the prostaglandin inhibitor, indomethacin, enhanced the increase in null cells in the bone marrow and spleen of LLc-bearing mice. The number of null small lymphocytes expressing NK1.1, as detected by combined radioautographic and immunoperoxidase techniques, increased almost 30-fold in LLc-bearing mice. The number of Thy1lo small lymphocytes increased in parallel with null cells during EA tumor growth. The findings accord with the hypothesis that the null lymphocyte population produced in mouse bone marrow includes newly formed NK lineage cells which sequentially express NK1.1 and Thy1lo. The present work demonstrates that the populations of null, NK1.1+, and Thy1lo lymphocytes in mouse bone marrow expand rapidly during the early growth of transplanted tumors, the initial increase in null lymphocytes apparently being curtailed by prostaglandin production. The results suggest that the production of null lymphocytes in mouse bone marrow is responsive to tumor development, possibly providing cells to be involved in tumor-host interactions.

Expression of the "T19" and "null cell" markers on gamma delta T cells of the sheep

A 215 kDa molecule termed T19 marks CD4-CD8- T cells in sheep and cattle. In this report, we analysed the T19 or "null cell" panel of mAbs against gamma delta T cells of sheep, using a mAb specific for the gamma delta TCR. By two-colour immunofluorescence, all of the mAbs in the T19 panel reacted with gamma delta T cells or subsets thereof, although staining intensities and percentages of cells stained by the different mAbs indicated considerable heterogeneity for the T19 molecule. This probably results from differential expression of certain epitopes on T19. The reactivity of most of the mAbs for the 215 kDa T19 molecule was also confirmed by immunoprecipitation and SDS-PAGE.

Analysis of workshop antibodies to null cells on a non-T/non-B lymphocyte population

Non-T and non-B lymphocytes (null cells) were obtained by Sephadex G-10 depletion followed by treatment with mAbs to CD2 and MHC class II and complement. The enriched cells were principally CD5dim and contained greatly increased numbers of null lymphocytes. This methodology will be useful for null lymphocyte enrichment in examining cell surface molecules and functional attributes of null lymphocytes.

Suppressor function of hepatic mononuclear inflammatory cells during murine chronic graft-vs-host disease. I. Macrophage-enriched cells mediate suppression in the liver

Murine chronic graft-vs-host disease (CGBHD) to minor histocompatibility antigens (B10.D2----BALB/c) is characterized by inflammatory destruction of intrahepatic bile ducts, scleroderma-like skin lesions, and lymphoid involution. Spleen cells isolated from this model proliferate poorly when stimulated with mitogens. Previous reports indicate defective lymphocyte proliferation in this model is the result of active suppression induced by the graft-vs-host reaction in the spleen and is mediated by Thy 1.2-, sIg-, plastic nonadherent, splenic natural suppressor (NS) cells. To determine whether the intense CGVHD in the liver is associated with induction of suppression, we compared the suppressor activity of hepatic and splenic mononuclear inflammatory cells isolated concurrently during murine CGVHD. Both hepatic and splenic MC suppressed the proliferation of mitogen-stimulated normal spleen cells in a non-MHC, non-Mls restricted manner. T cells contributed to the suppressor activity of both populations. However, the suppressor activity of hepatic MC was mediated largely by a macrophage-enriched population of MC while that of splenic MC was mediated largely by NS cells.

Investigating monoclonal antibodies to bovine "null" cell antigens using two-colour immunofluorescence

Eighteen monoclonal antibodies (mAbs) putatively to non T4/T8 (null) cell antigens were tested by two-colour immunofluorescence and antibody binding inhibition (blocking), with one selected mAb (CC15) that previous studies had indicated to be specific for null cells. None of the other mAbs blocked binding of CC15 to lymphocytes. Three main patterns of reaction were observed in two-colour immunofluorescence studies: mAbs that stained the same cells as CC15, mAbs that only stained a sub-population of the cells that stained with CC15 and mAbs that stained a sub-population of the cells that stained with CC15 but also some cells that did not react with CC15.

IL-3 promotes production of IL-4 by splenic non-B, non-T cells in response to Fc receptor cross-linkage

A spleen cell population that lacks CD3, CD4, CD8, Thy-1, B220, and class II major histocompatibility complex cell-surface markers (non-B, non-T cells) produces IL-4 when cultured in wells coated with IgE. Their production of IL-4 in response to plate-bound (PB)-IgE is strikingly enhanced by IL-3, and in the presence of IL-3, these cells also produce IL-4 in response to PB-IgG2a. The effect of IL-3 is not mimicked by IL-1, IL-2, IL-5, IL-6, IL-7, granulocyte-macrophage CSF (GM-CSF) or IFN-gamma. Non-B, non-T cells cultured with IL-3 for 12 h acquire the capacity to produce enhanced amounts of IL-4 in response to subsequent culture with PB-Ig even if IL-3 is omitted from the second culture. Irradiated cells also respond to IL-3 with enhanced capacity to produce IL-4 to PB-Ig, indicating that cell proliferation is not required for the effect of IL-3. The IL-3 effect can be obtained in vivo; treatment of mice with a total dose 90,000 U of synthetic IL-3 over a 3-day period results in the presence of splenic and peritoneal cavity non-B, non-T cells that produce enhanced amounts of IL-4 in response to PB-Ig. The FcR that mediates the response to PB-IgE appears to be Fc epsilon RI because cells can be sensitized with IgE anti-DNP mAb, washed, cultured for 15 h at 37 degrees C, washed again, and stimulated to produce IL-4 with 0.1 to 1 ng/ml of TNP10-OVA. IL-3 does not appear to mediate its function by increasing the number of Fc epsilon RI because it can exert its effect when cultured with non-B, non-T cells after they have been sensitized with IgE anti-DNP. However, IL-3 pretreatment does affect the signaling process in that non-B, non-T cells sensitized with IgE anti-DNP show strikingly reduced production of IL-4 to concentrations of TNP10-OVA of 100 ng/ml or more whereas cells pretreated with IL-3 show little or no diminution in IL-4 production at concentrations of TNP10-OVA up to 1 microgram/ml.

A distinct population of nonphagocytic and low level CD4+ null lymphocytes produce IFN-alpha after stimulation by herpes simplex virus-infected cells

Human PBMC were stimulated for 6 h in vitro by HSV or Sendai virus (SV) and analyzed by flow cytometry. IFN-alpha producing cells (IPC) were identified through their content of IFN-alpha mRNA by in situ hybridization using a 35S-labeled IFN-alpha 2 cRNA probe. The IPC induced by HSV-infected WISH cells lacked capacity to adhere to and phagocytose latex particles. The induction of IFN-alpha by free infectious SV occurring in monocytes was abolished by phagocytosis of latex particles present in the cultures during the induction period. Such latex particles actually enhanced the IFN-alpha response induced by glutaraldehyde-fixed HSV- or SV-infected WISH cells or by free intact HSV. The HSV-induced IPC did not express the CD14 Ag expressed on monocytes. Cell sorting was performed on HSV-induced PBMC labeled with phycoerythrin-conjugated anti-CD3 and FITC-conjugated anti-CD4 mAb. A small population consisting of 1.4% of all PBMC, which was CD3- but expressed low but significant levels of CD4, contained the majority of the IPC with a 50-fold increase of their frequency. This cell population had a forward- and right-angle light scatter different from typical monocytes/macrophages. The results therefore further delineate IPC among PBMC into monocytes, being stimulated by viruses such as SV. Another distinct population of infrequent but highly efficient IPC, tentatively designated natural IFN-alpha producing cells, is activated by stimuli such as HSV.

Changes of lymphocyte subsets in peripheral blood before and after operation of patients with advanced ovarian carcinoma

Comparison was made between lymphocyte subsets in peripheral blood from patients with benign ovarian tumor and those with advanced ovarian carcinoma. In addition, changes of lymphocyte subsets of patients with ovarian carcinoma before and after operation were also examined. The percentage and absolute number of CD3-/HLA-DR+ (B cells) in peripheral blood from patients with advanced ovarian carcinoma were significantly lower than values from patients with benign ovarian tumor, whereas both percentage and absolute number of CD3-/HLA-DR- (null cells) cells in patients with advanced ovarian carcinoma were significantly higher. Although there was no significant difference in natural killer (NK) cell subsets (CD57+ CD16- and CD57+ CD16+ cells) between patients with benign ovarian tumor and ovarian carcinoma, the percentage and absolute number of CD57-/CD16+ (highly differentiated NK cells) cells in patients with ovarian carcinoma were significantly higher than those in patients with benign ovarian tumor. Both the absolute number and percentage of CD3+/HLA-DR+ (activated T cells) cells in ovarian cancer patients with minimal residual tumors after operation were significantly increased, compared to the levels before operation, while the values in the patients with large residual tumors were significantly decreased. In addition, the percentage and absolute number of CD3-/HLA-DR- (null cells) cells in the patients with minimal residual tumors were significantly decreased after operation, while values in the patients with large residual tumors remained unchanged before and after operation. The patients with minimal residual tumors after operation were characterized by a significant increase in the percentage of CD57- CD16+ (highly differentiated NK cells) cells. On the other hand, in the patients with large residual tumors no change of the NK cell subsets was observed before and after operation.

Infection with Nippostrongylus brasiliensis or injection of anti-IgD antibodies markedly enhances Fc-receptor-mediated interleukin 4 production by non-B, non-T cells

Non-B, non-T cells from spleen and bone marrow of naive mice produce IL-4 upon stimulation by plate-bound IgE or IgG2a in the presence of IL-3. Infection of mice with Nippostrongylus brasiliensis (Nb) or injection of anti-IgD antibodies, treatments known to cause striking polyclonal IgE responses, increase the number of splenic non-B, non-T cells and cause 10-30-fold increase in IL-4 production by a standard number of these cells. In Nb-infected mice, IL-4 producing non-B, non-T cells can be found in the lungs, a site through which Nb larvae migrate. Non-B, non-T cells from anti-IgD-injected mice produce IL-4 in response to anti-IgE antibodies, indicating that these cells have been sensitized in vivo with IgE and that crosslinkage of such IgE can lead to stimulation of lymphokine production. Similarly, non-B, non-T cells from Nb-infected mice produce IL-4 upon stimulation with Nb-antigen, indicating that antigen can also crosslink receptors on in vivo sensitized non-B, non-T cells and stimulate lymphokine production. The striking increases in the IL-4-producing capacity of the splenic non-B, non-T cell population in anti-IgD-injected and Nb-infected mice and the in vivo sensitization of these cells strongly suggests that they may have an important role in lymphokine production in helminthic infections and other situations marked by striking elevations of serum IgE levels.

[Peripheral lymphocyte populations in patients treated with pelvic and mediastinal radiotherapy]

Solid tumor bearing patients often show a large variety of immunologic alterations: increase in immune complexes number, reduced NK activity, decreased IL-2 production, T4/T8 reverse and s.o. Most literature data generally concern chemotherapy and/or radiotherapy pretreated patients, so it is difficult to relate the immunological alterations with either antineoplastic treatments or the disease itself. We tried to evaluate any possible alteration of immunological parameters in patients with solid neoplasms who underwent radiotherapy on mediastinum or pelvis. The aim was to detect any variation in peripheral lymphoid sub-populations (even per site of irradiation) and a possible activation of an immune therapy. The evaluable patients were 38 (12 treated with surgery). The minimum dose delivered was 5000 cGys through conventional fractionation. The immunological parameters (T, B, N, T4, T8, H/S) were evaluated before the treatment, at the end and every 2 months during follow-up. Cases were analyzed also per single irradiation volume. No statistically significant variation in immunological parameters was found, although suppressor activity was confirmed as prevailing in immune responsiveness of cancer patients. Thus any significant correlation between immunological state and disease evolution or response to treatment has still to be verified.

[The ratio of various lymphocyte populations in bacillary dysentery and nonspecific ulcerative colitis]

The comparative study of the content of different lymphocyte populations of the peripheral blood in pathological states accompanied by lesions of the mucous membrane of the large intestine has been made. In shigellosis patients the accumulation of lymphocytes having the signs of young post-thymic forms (theophylline-dependent populations) and functionally active forms (Ea-rosette-forming cells) occurs in the circulating blood. In unspecific ulcerous colitis only an increase in the number of immature lymphocytes (theophylline-dependent lymphocytes and autorosette-forming cells) is observed. In both pathological states an increase in the number of O-lymphocytes with Fc gamma-receptors occurs in the circulation blood.

[Effects of radiotherapy on lymphocyte populations in lung cancer]

The authors report on the results of the immune monitoring of a study population of 31 patients with lung cancer who were treated with radiotherapy. A synthetic thymic pentapeptide, thymopentin, was employed whose effect was evaluated on the immunological parameters analyzed. After radiotherapy, a considerable and homogeneous decrement was observed in several lymphocytic subsets (less sensible in activated T-cells), together with a progressive decrement in the helper/suppressor ratio, in the long run. Monocytes and null cells showed more radioresistance. Thymopentin had no influence on the tested immunological parameters up to 6 months after radiotherapy; later on, a slightly more balanced helper/suppressor ratio could be noticed in the surviving patients who had been treated with thymopentin.

Cell populations in human early pregnancy decidua: characterization and isolation of large granular lymphocytes by flow cytometry

Cell populations of human pregnancy decidua, obtained by enzymic digestion from first trimester samples, were analysed by flow cytometry after labelling with monoclonal antibodies. The majority of these decidual cells (75%) were of bone marrow origin. The most abundant cell type expressed antigens characteristic of large granular lymphocytes (LGL), although macrophages and small numbers of classical T cells were also present. Three subsets of decidual LGL can be defined by single-and double-antibody labelling. Most decidual LGL are positive for NKH1, a marker of peripheral blood LGL, but negative for CD16, the Fc receptor of NK cells, and for the T-cell markers CD3 and CD5. About half the NKH1-positive cells also express CD2, associated with the E-rosette receptor, and are identical to the CD3-negative/CD2-positive cells reported previously in early pregnancy decidua. The NKH1-positive cells apparently correspond to a minor subset of peripheral blood LGL. The remaining decidual LGL are positive for CD16 and negative or only dimly positive for NKH1, and are similar to the major type of peripheral blood LGL. After purification by flow cytometry, the NKH1-positive cells were demonstrated to be of similar size to, but slightly higher granularity than, lymphocytes, whereas the CD16-positive cells were larger and more granular. The possible role of decidual LGL in modulating placental development is discussed.

Isolation of an antigenically "null" cell line from pig peripheral blood mononuclear cells

A new pig cell line (A4) isolated from a primary culture of pig peripheral blood mononuclear cells was characterized. A4 was demonstrated to be morphologically, antigenically and functionally distinct from the more commonly isolated pig lymphoblastoid B cell lines (e.g. P-SC). When the A4 cell line and clones derived from it were tested against a panel of monoclonal antibodies, which define specific subpopulations of pig mononuclear cells, little or no reactivity was observed. The A4 cell line, unlike the P-SC cell line, was unable to induce a mixed lymphocyte reaction. The amount of immunoglobulin secreted by A4 cells as detected by an ELISA was reduced compared to that produced by P-SC cells. The P-SC cell lines produced an IL-1-like factor, whereas no IL-1-like activity was found in the A4 supernatant. The A4 cell line appeared to be a null cell in respect to the P-SC cell line properties; only the slight amount of immunoglobulin produced suggested that the A4 cell line is of the B cell lineage. An association of viral particles with cells of the A4 morphology and null antigenic characteristics was observed and may provide an explanation for the reduced B cell properties of A4 cells.

Lymphocyte subpopulations during acute and convalescence phases of malaria

Lymphocytes of normal healthy persons were separated from blood by Ficoll-Hypaque gradient centrifugation and iron-magnet application. peripheral blood lymphocytes (PBL) were stained by various dye-labeled monoclonal antibodies. Cells positive for specific surface markers were enumerated by a fluorescence activated cell sorter (FACS) and fluorescence microscope (FM). The results revealed that the percentages of cells positive with one monoclonal antibody counted by these two techniques were similar while the percentages of cells with double staining were higher when counted by FACS than by FM. Lymphocyte subpopulations of 18 patients infected with Plasmodium falciparum during acute and convalescence period were studied. Lymphocytopenia occurred during the acute infection while total white blood cell counts were normal. PBL of the patients were stained with OKT3, OKT4, OKT8, Leu-11 and a combination of Leu-7, Leu-1 monoclonal antibodies. The absolute numbers of all lymphocyte subpopulations were decreased during the acute infection while T8 positive cells were decreased in both percentage and absolute number. Thus T4:T8 ratio (1.7:1) became higher than normal (1.3:1) at this period. During convalescence phase, absolute numbers and percentages of Leu-7+, Leu-1+ and perhaps Leu-7+, Leu-11- cells which had low NK cell activity were significantly higher than during acute illness. The finding might explain why the NK cell activity was low during the convalescence period.

The T-lymphocyte colony-forming cell (T-CFC): in vitro studies of progenitors and progeny

The lineage of T-lymphocyte colony-forming cells (T-CFC) and the phenotype of the progeny of T-CFC have not yet been well-defined. To characterize the progenitor cells and progeny of the T-CFC, we separated normal human peripheral blood lymphocytes into enriched lymphocyte subpopulations, stimulated with various mitogens and cultured in a semisolid agar system. After 5 days, the number of colonies was counted, and the presence of CD4+ and CD8+ cells was determined in situ with FITC-conjugated monoclonal antibodies. Plating of B cells provided the lowest, T cells an intermediate and null cells the highest number of T-cell colonies (P less than 0.05). CD4+ and CD8+ cells produced equivalent numbers of T-cell colonies. T-cell colonies consisted of either CD4+ or CD8+ cells; mixed-cell colonies were rarely present. Plating of CD4+ or CD8+ cells produced both CD4+ and CD8+ colonies. We conclude that T-CFC exist in the CD4+, CD8+ and null-cell populations. In addition, T-CFC give rise to T-cell colonies possessing either CD4+ or CD8+ determinants.

Bovine T cells, B cells, and null cells are transformed by the protozoan parasite Theileria parva

The target cells for infection and transformation by Theileria parva were investigated. Peripheral blood mononuclear cells were reacted with monoclonal antibodies specific for bovine leukocyte differentiation antigens, sorted into subpopulations with a fluorescence-activated cell sorter, and infected in vitro with T. parva sporozoites. Infected cells were cultured at limiting dilution, and transformed clones were screened with monoclonal antibodies. The results indicated that B cells, T cells (including BoT4+ and BoT8+ cells), and null cells but not monocytes or neutrophils were transformed in vitro after infection with T. parva. After transformation, peripheral blood T cells and T-cell clones retained expression of most or all of the T-cell differentiation antigens including the mature T-cell marker recognized by monoclonal antibody IL-A27, BoT2, and BoT4 or BoT8, and some cells acquired a low level of expression of BoT4, BoT8, or the null cell marker recognized by monoclonal antibody IL-A29. T. parva-transformed null cells retained expression of the IL-A29 determinant and acquired expression of BoT2 and BoT8 but not the IL-A27 determinant or BoT4. T. parva-transformed B cells in most instances lost expression of surface immunoglobulin and never acquired expression of the IL-A27 determinant, BoT2, BoT4, or BoT8, although some cells acquired a low level of expression of the null cell marker recognized by monoclonal antibody IL-A29. Further studies on cell lines and clones grown in vitro from populations isolated from T. parva-infected cattle suggested that the majority of the in vivo T. parva-transformed cells were of T-cell origin.

Subpopulations of T lymphocytes emigrating in venous blood draining pig thymus labelled in vivo with fluorochrome

The emigration of labelled thymus cells in the pig was studied directly in blood draining the large right distal cervical lobe of the thymus after controlled labelling with FITC delivered through cannulated branches of a main thymic artery and vein by temporary ex vivo perfusion at body temperature. Roughly 1% of thymic cells emigrated per day. Unlike most thymocytes, which are small, the size spectrum of thymic emigrants is slightly larger than that of typical blood lymphocytes. Surface-marker studies show that the surface phenotypes of the emigrants differ from both typical thymus and peripheral blood lymphocytes. Although the emigrants resemble thymocytes in the high proportion of strong rosettes formed with sheep red blood cells (RBC), they rosette poorly with pig red cells, particularly in the unenhanced saline test, in this respect behaving like blood lymphocytes. The peripheral T-cell subset bearing a Fc receptor is almost absent in thymus, but is well represented among the emigrants which thus resemble corticosteroid-resistant thymocytes in the pig. The large population of thymus-dependent Null lymphocytes in young pig blood apparently arise in thymus since they constitute 1/3 of emigrants, although only forming less than 10% of thymus cells. This emigration of thymic cells is discussed in relation to its implications for the turnover of known functional peripheral T-cell populations.

Dopamine receptors in immunohistochemically characterized null cell adenomas and normal human pituitaries

Dopamine receptors were analyzed in plasma membranes from five null cell adenomas and five normal human pituitary tissues by [3H]spiperone binding. One prolactin (PRL)-producing, one growth hormone (GH)-producing, and an adrenocorticotropic (ACTH)-producing adenoma were also analyzed for dopamine receptors. Immunohistochemical staining showed that all null cell adenomas were positive for chromogranin A, while 20 to 30% of cells in each normal pituitary stained for this marker. The dissociation constant (Kd) and maximal binding capacity (Bmax) were 1.07 +/- 0.49 nM and 148 +/- 34 fmol/mg protein for null cell adenomas and 1.23 +/- 0.20 nM and 107 +/- 21 fmol/mg protein for normal pituitary tissues. The one PRL adenoma had a similar Kd but had a 5.6-fold higher Bmax than the mean Bmax for the null cell adenomas. These results indicate that immunohistochemically characterized null cell adenomas as well as normal pituitaries express dopamine receptors, but that the binding sites in null cell adenomas are much less those in PRL-secreting adenomas.

Bovine antibody dependent cell-mediated cytotoxicity (ADCC) effector cells

ADCC effector cells from bovine blood were separated by centrifugation, adherence and rosetting techniques. Each enriched cell population, peripheral blood mononuclear cells (PBM), null lymphocytes, monocytes and neutrophils, was then examined for its capacity to mediate ADCC. Utilizing heterologous sensitizing antisera it was found that monocytes had approximately twice the ADCC activity of null lymphocytes and that neutrophils had essentially no activity. However, when homologous sensitizing antisera were used it was found that neutrophils possessed the greatest activity followed by monocytes and null cells. Results confirm the existence of an ADCC active null lymphocyte in the bovine.

Natural suppressor (NS) activity from murine neonatal spleen is responsive to IFN-gamma

Natural suppressor (NS) cell activity is the ability of apparently unprimed "null" cells to nonspecifically suppress immune responses. Previously we have shown that NS cell activity from the spleens of mice undergoing chronic graft-vs-host disease (GVHD) is enhanced in vitro by activated T cell signals (e.g., Con A supernatant [CAS]). Here we asked if the naturally occurring suppressor activity found in the neonatal mouse spleen is caused by NS cells, and if so whether this NS activity is also responsive to T cell signals. Finally, we wanted to identify the material in the CAS to which the NS cells respond. Spleen cells from (BALB/c X B10.D2)F1 neonates contain potent, genetically unrestricted suppressor activity toward normal mitogen responses. The cells responsible for this suppression are nonadherent, Thy-, Ig- and are thus by definition NS cells. Neonatal spleen NS cells suppress the indicator Con A response of all mouse strains tested, but their behavior with regard to LPS responses is different. They significantly inhibit the indicator LPS response of allogeneic strains, but are less inhibitory of LPS-stimulated syngeneic (BALB/c X B10.D2)F1 and parental strains. However, the addition of CAS to these latter cultures enhances the NS inhibition of the LPS response to the level of suppression seen with a Con A response. Two lymphokines were able to replace the CAS. Recombinant interferon-gamma (rIFN-gamma) closely mimics the activity found with whole CAS, with low concentrations (1 U/well) being capable of enhancing the neonatal NS activity to near-maximal levels. Recombinant interleukin 2 (rIL 2) is also capable of stimulating the neonatal NS activity to near maximum. However, the rIL 2 must be added at much higher concentrations, taking greater than 50 U/well to get maximum activation of NS suppression. The addition of anti-IFN-gamma antiserum to these LPS suppression assays removes the ability of CAS to activate the neonatal NS cells. Anti-IFN-gamma antiserum also removes the ability of rIL 2 as well as rIFN-gamma to activate the NS cells. It thus appears that the rIL 2 is working by its ability to stimulate IFN-gamma production. Anti-IFN-gamma also removes the ability of the neonatal NS cells to suppress a Con A response. Therefore, it appears that neonatal splenic NS cells respond to, and are activated by, IFN-gamma to carry out their suppressive activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Peripheral blood leucocytes subpopulation dynamics during Trypanosoma congolense infection in Boran and N'Dama cattle: an analysis using monoclonal antibodies and flow cytometry

A panel of monoclonal antibodies (MoAb) with specificities for bovine leucocyte subsets were used in conjunction with routine haematological procedures to analyse sequential changes in peripheral blood leucocyte populations during the course of tsetse fly-transmitted Trypanosoma congolense infection in trypanotolerant N'Dama and trypanosusceptible Boran cattle. Subsequent to the first parasitaemic wave, the N'Dama cattle maintained packed cell volumes (PCV) above 22 and lower levels of parasitaemia than Boran throughout the 160 days of the experiment. In contrast, the Borans developed severe anaemia and required curative drug therapy (i.e., PCV dropped to less than 15) by 55 days (range: 22-55 days) post infection. There were significant (P less than 0.05) decreases in total white blood cells and total lymphocytes from pre-infection levels to the first peak of parasitaemia (day 16 post-infection) in both groups. Flow cytometric analyses using MoABs revealed that this change was due to an absolute decrease in T cells expressing BoT2 and either BoT4 or BoT8, surface immunoglobulin M-positive (sIgM+) B cells, and null cells which did not express T cell, B cell or monocyte markers. During this period there was significant variation over time, but no overall increase or decrease, in the number of cells expressing class II major histocompatibility (MHC) molecules or monocyte markers, or in the number of circulating neutrophils or eosinophils. The BoT4/BoT8 ratios were significantly (P less than 0.01) increased in both groups of infected animals at the first peak of parasitaemia. After day 22 in the infected N'Damas and in the Borans which required drug therapy, there was a leucocytotic response characterized by an increase in the total number of B cells, T cells, and null cells. Prior to infection and throughout the course of the experiment N'Dama cattle had significantly (P less than 0.01) higher numbers of B cells and null cells than Boran.

Cellular subsets involved in cell-mediated immunity to murine Plasmodium yoelii 17X malaria

Cell mediated immunity to nonlethal Plasmodium yoelli 17X (PY17X-NL) was examined in the CBA/CaJ mouse by adoptive transfer of sensitized T lymphocyte subsets. In intact mice, PY17X-NL causes a self-limiting infection with parasitemia levels ranging from 10 to 25% of total red blood cells. Upon recovery, mice are refractory to subsequent challenge with the homologous parasite. In T cell-depleted mice, PY17X-NL infections are extremely virulent and result in death of the host after parasitemia levels reach 50% or higher. The transfer of either Lyt-1 T cells or Lyt-2 T cells from immune animals into normal, naive animals produced accelerated recovery to subsequent infection. However, this adoptive transfer of immunity by either subset was dependent upon the presence of an I-J+, Lyt-null cell in the immune population. T cell deprivation precluded the ability of animals to control blood-stage infections. When T cell-depleted mice were reconstituted with naive, Ig-negative (T cell-enriched) spleen cells, parasitemia levels were controlled and the parasites were eliminated. When T cell-deprived animals were reconstituted with naive Lyt-1+2-, Ig-negative spleen cells, they experienced twofold higher parasitemias of longer duration than mice receiving unfractionated cells. Two of six of these Lyt-1 mice died of fulminant infections, suggesting that the presence of naive Lyt-2 cells enhances the degree of protection. Immune Lyt-2 T cells were highly protective in T cell-depleted animals. Protection by sensitized Lyt-1 T cells correlated with the induction of a monocytosis. On the other hand, protection by Lyt-2T cells occurred in the absence of monocytosis. The possibility that the immunity induced by each T cell subset is mediated by a different effector mechanism is discussed.

The interaction of recombinant IL-2 with human resting lymphocytes: blocking effects of monoclonal antibodies to IL-2 receptors

Several lines of evidence suggest that subsets of resting lymphocytes naturally express interleukin-2 receptors (IL-2.R). Recombinant IL-2 (rIL-2) induced the enhancement of natural killer (NK) activity, the generation of activated killer (AK) cells, the proliferation of resting lymphocytes, and the production of interferon-gamma (IFN-gamma) in lymphocyte cultures. The subsets of lymphocytes mediating these responses appeared to be heterogeneous, but reside predominantly in nylon wool-passed non-T, non-B cells ("null cells" or T3- cells); in response to rIL-2, only Leu 11+T3- cells showed enhanced NK activity, and both Leu 11+T3- and Leu11-T3- cells showed predominantly AK activity, proliferation and production of IFN-gamma. These findings suggest that the T3- fraction (null cell fraction) contains predominantly cells expressing IL-2.R at the resting state. Unlike the case with activated T cells, however, none of these responses was blocked by any of three monoclonal antibodies to IL-2.R, including anti-Tac antibody at any dilution. These results indicate that IL-2.R on the resting T3- cells possess unique biological features compared to those on activated T or B cells. A most likely explanation is that T3- cells possess higher affinity IL-2.R than activated T or B cells. Other possibilities are also discussed.

Human acute unclassified leukemia with a unique t(4;17) chromosomal translocation expresses T lymphoid and myeloid surface antigens after in vitro culture

Bilineage differentiation along both the T lymphoid and the myeloid lineage while in in vivo diffusion chamber (DC) and in vitro suspension culture was observed in a case of acute unclassified leukemia (null-AL) and t(4;17). Prior to culture, the blast cells were TdT and la positive but did not express any lineage-specific antigenic markers. Furthermore, the immunoglobulin heavy chain and T cell receptor beta-chain genes were in germline configuration. Cytogenetically, all metaphases had the unique translocation t(4;17) (q25;q23) prior to and after culture, supporting the leukemic origin of the cells. During both DC culture and suspension culture with and without tetradecanoyl-phorbol-acetate (TPA), a substantial increase in the absolute and relative number of cells expressing both myeloid and T lymphoid antigenic markers occurred. Double-fluorescence analysis demonstrated the expression of antigenic markers of both lineages on the same population of cells, and electron microscopy revealed the induction of myeloperoxidase after both DC and suspension culture. Immunoglobulin heavy chain and T cell receptor beta-chain genes remained in germline configuration after treatment with TPA, when analyzed with JH and CT beta probes, respectively. These findings indicate that this case represents a null-AL with dual-lineage capabilities, which has probably arisen from the malignant transformation of a bipotential stem cell of lymphoid and myeloid progeny.

The expanded null cell compartment in ageing: increase in the number of natural killer cells and changes in T-cell and NK-cell subsets in human blood

Analysis of the subpopulations of mononuclear cells in human blood in ageing has revealed a striking increase in the number of null cells, defined as non-T, non-B, non-monocyte cells, and a decrease in the number of T and B cells. By using recently developed monoclonal antibodies against natural killer cells in combination with T-cell markers in two-wavelength immunofluorescence, we were able to define 13 subpopulations of mononuclear cells and compare them in two groups of persons, respectively aged 25-34 and 75-84 years, all fulfilling the stringent admission criteria for immunogerontological studies described in the SENIEUR protocol, and thus all to be considered as optimally healthy and immunologically uncompromised. We found that the increased null cell population in the aged is a result of an increase in the numbers of NK cells, mostly the CD16+Leu7+ subset. The number of CD8+ suppressor/cytotoxic cells is decreased. This is due to a decrease of the number of CD8+Leu7- cells. All NK and T-cell subsets bearing the Leu7 antigen, namely CD16+ Leu7+, CD4+Leu7+ and CD8+Leu7+, are increased. These changes can be due to defects of the ageing immune system, but they can also represent the optimal state of the immune system in the healthy aged and may be linked to survival. These values can be used as reference values for the 75-84 years age group and serve to monitor attempts to reconstitute the immune defects in ageing.

[Distribution of lymphocytes according to the cell cycle phases in T, B, D and O populations in human blood and the immune system organs of animals vaccinated against cholera]

The work presents the results of the study (carried out by the method of continuous flow cytofluorometry) of changes in the distribution of lymphocytes and their populations (obtained by means of distributing cell electrophoresis) according to the phases of the cell cycle (G0 + G1; S; G2 + M) in the blood and spleen of guinea pigs, as well as in the blood of humans, before and after immunization with cholera vaccine. The results of the determination of DNA-synthesizing lymphocytes in the blood of immunized humans and animals have been shown to serve as an objective characteristic for the complex evaluation of the biological activity of cholera vaccines.