Antigen recognition by MHC-incompatible cells of a human mismatched chimera

Tetanus toxin (TT)-specific T cell clones of donor origin were obtained from a patient with severe combined immunodeficiency (SCID) successfully reconstituted by transplantation of allogeneic fetal liver and thymus cells from two different donors performed 10 yr ago. A series of these clones recognized TT in the context of "allo" class II HLA determinants expressed by recipient APC. The restriction element of two T cell clones with the HLA phenotype of the first donor (HLA-DR1,8) and one T cell clone with the HLA phenotype of the second transplant (HLA-DR3,9) was HLA-DR4 of the recipient, whereas other T cell clones derived from the second transplant recognized TT in the context of HLA-DR5 of the recipient's APC. These latter T cell clones were not able to proliferate in response to TT when autologous APC were used. These data demonstrate that recipient and donor cells having different HLA phenotypes could cooperate across the allogeneic barrier and that MHC restriction of antigen (Ag) recognition is independent from the MHC genotype of the T cells but is influenced by the environment in which the T cells mature. We also isolated T cell clones that were able to recognize processed TT presented by all allogeneic EBV cell lines tested, indicating that the Ag specificity of these clones was not restricted by a particular class II MHC molecule. The Ag-specific proliferative response of one of these clones could be blocked by anti-class II MHC mAbs. These results demonstrate that in addition to Ag recognition in the context of specific class II MHC Ags, other types of Ag-specific responses may occur in this human chimera. It is not clear whether this "allo" plus Ag recognition is the result of education of transplanted fetal cells in the host thymus. Taking into consideration our previous findings indicating that alloreactive T cell clones specific for the recipient cells could be isolated in vitro from the PBL of the same patient, our data suggest that the mechanism for deletion of self-reactive clones and the generation of MHC-restricted responses are different.

Genomic organization of the human T-cell antigen-receptor alpha/delta locus

Two clusters of overlapping cosmid clones comprising about 100 kilobases (kb) at the human T-cell antigen-receptor alpha/delta locus were isolated from a genomic library. The structure of the germ-line V delta 1 variable gene segment was determined. V delta 1 is located 8.5 kb downstream of the V alpha 13.1 gene segment, and both V segments are arranged in the same transcriptional orientation. The V alpha 17.1 segment is located between V delta 1 and the D delta, J delta, C delta region (containing the diversity, joining, and constant gene segments). Thus, V delta and V alpha segments are interspersed along the chromosome. The germ-line organization of the D delta 2, J delta 1, and J delta 2 segments was determined. Linkage of C delta to the J alpha region was established by identification of J alpha segments within 20 kb downstream of C delta. The organization of the locus was also analyzed by field-inversion gel electrophoresis. The unrearranged V delta 1 and D delta, J delta, C delta regions are quite distant from each other, apparently separated by a minimum of 175-180 kb.

IgE production by normal human B cells induced by alloreactive T cell clones is mediated by IL-4 and suppressed by IFN-gamma

Seven T cell clones were established from mixed leukocyte cultures in which PBMC from two healthy donors and from one patient suffering from the hyper-IgE syndrome were stimulated by the irradiated EBV-transformed B cell lines JY or UD53. Five of seven T cell clones, after activation by co-cultivation with JY or UD53 cells, induced a low degree of IgE production by normal blood B cells. In one experiment in which the normal B cells could activate the T cell clones directly, IgE production was also observed in the absence of the specific stimulator cells. IgE production was also obtained with supernatants of the T cell clones collected 4 to 5 days after activation by their specific stimulator cells. In addition, the supernatants induced IgG, IgA, and IgM synthesis. All seven clones produced variable concentrations of IL-4 and IFN-gamma. The clones FA-28 and BG-39, which failed to induce IgE synthesis, produced, compared with the other clones tested, relatively high quantities of IFN-gamma (4700 and 2500 pg/ml, respectively). These high levels of IFN-gamma accounted for the lack of induction of IgE synthesis, because in the presence of a polyclonal anti-IFN-gamma antiserum, supernatants of FA-10 and BG-39 induced significant IgE production. In addition, the low degree of IgE production induced by supernatants of two other T cell clones (FA28 and BG24) was 15- and 3-fold enhanced, respectively, in the presence of the anti-IFN-gamma antiserum. IgE synthesis by normal B cells was also induced by rIL-4, indicating that IL-4 present in T cell clone supernatants was responsible for induction of IgE production. This notion was supported by the finding that IgE production induced by supernatant of BG-24 was strongly inhibited by a polyclonal anti-IL-4 antiserum. In contrast, IgG and IgA production induced by supernatant of BG-24 were not significantly affected by the anti-IL-4 antiserum. Only a slight inhibition of IgM synthesis was observed. Collectively, our results indicate that both recombinant and naturally produced IL-4 induce normal human B cells to synthesize IgE. However, final IgE production induced by T cell clone supernatants is the net result of the inducing and suppressive effects of IL-4 and IFN-gamma respectively, that are secreted simultaneously by the T cell clones upon activation.

Triggering of cytotoxic T lymphocytes and NK cells via the Tp103 pathway is dependent on the expression of the T cell receptor/CD3 complex

The expression and function of the T cell activation molecule Tp103 on human cloned cytotoxic CD3+ and CD3- cells were studied. All in vitro growing CD3+ and CD3- clones expressed Tp103 regardless of their phenotype and the expression of a CD3-associated TCR complex. Whereas the CD2 pathway was functional in all these clones, only CD3-expressing clones could be triggered via Tp103 to kill target cells. In contrast, both CD2 and Tp103 pathways were suppressed after modulation of the TCR complex with anti-CD3 mAb. This indicates that the function of Tp103 but not of CD2 is dependent on the expression of a functional Ag receptor on cytotoxic T cells. Furthermore, modulation of the Ag receptor induces a state of unresponsiveness in cytotoxic T cells that cannot be attributed to just the removal of the CD3/TCR complex from the cell membrane.

IgE production by normal human B cells induced by alloreactive T cell clones is mediated by IL-4 and suppressed by IFN-gamma

Seven T cell clones were established from mixed leukocyte cultures in which PBMC from two healthy donors and from one patient suffering from the hyper-IgE syndrome were stimulated by the irradiated EBV-transformed B cell lines JY or UD53. Five of seven T cell clones, after activation by co-cultivation with JY or UD53 cells, induced a low degree of IgE production by normal blood B cells. In one experiment in which the normal B cells could activate the T cell clones directly, IgE production was also observed in the absence of the specific stimulator cells. IgE production was also obtained with supernatants of the T cell clones collected 4 to 5 days after activation by their specific stimulator cells. In addition, the supernatants induced IgG, IgA, and IgM synthesis. All seven clones produced variable concentrations of IL-4 and IFN-gamma. The clones FA-28 and BG-39, which failed to induce IgE synthesis, produced, compared with the other clones tested, relatively high quantities of IFN-gamma (4700 and 2500 pg/ml, respectively). These high levels of IFN-gamma accounted for the lack of induction of IgE synthesis, because in the presence of a polyclonal anti-IFN-gamma antiserum, supernatants of FA-10 and BG-39 induced significant IgE production. In addition, the low degree of IgE production induced by supernatants of two other T cell clones (FA28 and BG24) was 15- and 3-fold enhanced, respectively, in the presence of the anti-IFN-gamma antiserum. IgE synthesis by normal B cells was also induced by rIL-4, indicating that IL-4 present in T cell clone supernatants was responsible for induction of IgE production. This notion was supported by the finding that IgE production induced by supernatant of BG-24 was strongly inhibited by a polyclonal anti-IL-4 antiserum. In contrast, IgG and IgA production induced by supernatant of BG-24 were not significantly affected by the anti-IL-4 antiserum. Only a slight inhibition of IgM synthesis was observed. Collectively, our results indicate that both recombinant and naturally produced IL-4 induce normal human B cells to synthesize IgE. However, final IgE production induced by T cell clone supernatants is the net result of the inducing and suppressive effects of IL-4 and IFN-gamma respectively, that are secreted simultaneously by the T cell clones upon activation.

Triggering of cytotoxic T lymphocytes and NK cells via the Tp103 pathway is dependent on the expression of the T cell receptor/CD3 complex

The expression and function of the T cell activation molecule Tp103 on human cloned cytotoxic CD3+ and CD3- cells were studied. All in vitro growing CD3+ and CD3- clones expressed Tp103 regardless of their phenotype and the expression of a CD3-associated TCR complex. Whereas the CD2 pathway was functional in all these clones, only CD3-expressing clones could be triggered via Tp103 to kill target cells. In contrast, both CD2 and Tp103 pathways were suppressed after modulation of the TCR complex with anti-CD3 mAb. This indicates that the function of Tp103 but not of CD2 is dependent on the expression of a functional Ag receptor on cytotoxic T cells. Furthermore, modulation of the Ag receptor induces a state of unresponsiveness in cytotoxic T cells that cannot be attributed to just the removal of the CD3/TCR complex from the cell membrane.

Interleukin 5 enhances interleukin 4-induced IgE production by normal human B cells. The role of soluble CD23 antigen

Interleukin 4 (IL 4)-induced IgE production by peripheral blood lymphocytes and tonsil cells from normal donors was enhanced in a dose-dependent fashion by IL 5. IL 5 tested alone was not effective. The synergistic effects of IL 5 were most pronounced at suboptimal IL 4 concentrations, whereas at saturating IL 4 concentrations (200-300 U/ml), IL 5 had no effect. Interferon-gamma (IFN-gamma) and F(ab')2 fragments of monoclonal antibody 25 directed against the CD23 antigen, that blocked IL 4-induced IgE synthesis, also inhibited the production of IgE in the presence of combinations of IL 4 and IL 5, indicating that IL 5 potentiates the activation pathway through which IL 4 induces IgE production. In contrast, IL 4 (50 U/ml) blocked IL 5-induced IgA synthesis. IL 5 was ineffective in inducing the release of soluble CD23 (sCD23), but in the presence of IL 4 an enhanced release of sCD23 was observed, provided IL 4 was present at suboptimal concentrations. IFN-gamma completely blocked sCD23 release induced by IL 4 and IL 5. These results demonstrate that there is a strong quantitative correlation between sCD23 release and induction of IgE synthesis. sCD23 fraction-correlation between sCD23 release and induction of IgE synthesis. sCD23 fractionated from the Epstein-Barr virus-transformed B cell line RPMI 8866 was ineffective in inducing IgE production. However, sCD23 acted synergistically with suboptimal concentrations of IL 4. sCD23 did not modulate the IgE response at saturating concentrations of IL 4. Collectively, these data indicate that sCD23 plays an important regulatory role in the modulation of IL 4-induced IgE synthesis mediated by IFN-gamma and IL 5.

Autoreactive T cell clones specific for class I and class II HLA antigens isolated from a human chimera

T cell clones of donor origin that specifically react with recipient cells were obtained from a SCID patient successfully reconstituted by allogeneic fetal liver and thymus transplantation performed 10 yr ago. The majority of these clones displayed both cytotoxic and proliferative responses towards PBL and an EBV-transformed B cell line derived from the patient. In addition, these T cell clones had proliferative and cytotoxic responses towards the parental PBL, EBV cell lines, and PHA blasts. Blocking studies with anti-class I and anti-class II HLA mAbs indicated that the activity of the CD4+ T cell clones was specifically directed against class II HLA antigens of the recipient. On the other hand, the cytotoxic and proliferative responses of the CD8+ T cell clones were specific for class I HLA antigens which are ubiquitously expressed on the recipient cells. Thus, the establishment of transplantation tolerance observed in this stable human chimera is not due to the elimination of host-reactive T cells from the repertoire and suggests the presence of a peripheral autoregulatory suppressor mechanism.

Induction of the receptor for the Fc portion of IgA by secretory IgA on human T cell lines and T cell clones

Human colostral secretory IgA (SIgA; predominantly present in dimeric of polymeric forms) induces receptors for the Fc portion of IgA (Fc alpha R) on cloned and noncloned human T cell lines. The binding of SIgA to its FcR was isotype specific, since it was not inhibited by IgG or IgM. Binding of SIgA was also not affected by ovalbumin asialoglycoprotein. In addition, SIgA blocked the binding of directly fluorescein isothiocyanate-labeled SIgA in a dose-dependent fashion, whereas IgG and IgM were ineffective, confirming the specificity of the binding. Expression of Fc alpha R was specifically induced by SIgA, whereas serum IgA (predominantly present in monomeric form) had no effect. In addition, IgG, IgM and IgE were ineffective. This induction of Fc alpha R by SIgA was dose dependent. Optimal induction was observed at concentrations of 500 micrograms/ml after incubation times of 48 h. Fc alpha R were predominantly induced on T cell lines and T cell clones derived from tonsils. T cell lines and T cell clones established from peripheral blood could only occasionally be induced to express Fc alpha R. Induction of Fc alpha R expression was obtained both with CD4+ and CD8+ T cell clones. Fc alpha R were readily induced on T cell clones tested up to 6 days after activation by alloantigen. T cell clones tested 10-12 days after alloantigen activation failed to respond to SIgA. These results indicate that the inducibility of Fc alpha R is related to the activation stage of the T cell clones.

Human recombinant interleukin 4 induces normal B cells to produce soluble CD23/IgE-binding factor analogous to that spontaneously released by lymphoblastoid B cell lines

Surface-labeled Epstein-Barr virus (EBV)-transformed lymphoblastoid RPMI 8866 cells release in their supernatant a radiolabeled 25-kDa polypeptide which reacts with the Fc epsilon RL/CD23-specific monoclonal antibody (mAb) 25 and which binds to IgE but not IgG (IgE BF/sCD23). IgE BF/sCD23 had an isoelectric point of 4.5-5.0. The reactivity of mAb 25 with IgE BF/sCD23 allowed us to set up a radioimmunoassay for detection of IgE BF/sCD23 in cell culture supernatants. Supernatants from Fc epsilon RL/CD23+ cell lines were found to contain IgE BF/sCD23. Addition of human recombinant interleukin 4 (IL 4) to normal human B cells cultures induced the production of IgE BF/sCD23. Activation of B cells with anti-IgM antibody coupled to beads enhanced the IL 4-induced production of IgE BF/sCD23 when compared to nonactivated B cells. This correlates with the finding that anti-IgM antibody-activated B cells cultured with IL 4 express more Fc epsilon RL/CD23 than B cells cultured with IL 4 alone. The biochemical characteristics of radiolabeled IgE BF/sCD23 immunoprecipitated by mAb 25 from the supernatants of normal B cells cultured with IL 4 were identical to those of the IgE BF/sCD23 isolated from EBV-transformed cell line supernatants. Addition of interferon-gamma to B cells cultured with IL 4 strongly decreased the level of IgE BF/sCD23 in culture supernatants correlating with the observed decrease of Fc epsilon RL/CD23 on B cell surface. These data demonstrate that normal human B cells cultured in the presence of IL 4 produce an IgE-binding factor (sCD23) biochemically and antigenically equivalent to that spontaneously produced by EBV-transformed lymphoblastoid cell lines.

Role of p150,95 in adhesion, migration, chemotaxis and phagocytosis of human monocytes

The leukocyte function-associated antigen-1 (LFA-1), the C3bi receptor (CR3) and the p150,95 antigen belong to a family of leukocyte surface molecules consisting of bimolecular complexes with alpha chains of 170 kDa, 165 kDa and 150 kDa, respectively, and a common beta subunit with a mol. mass of 95 kDa. In order to determine the function of the p150,95 antigen on human monocytes and U937 cells, and to study the functional relationship between this antigen and LFA-1 or CR3, we investigated the influence of monoclonal antibodies (mAb) directed against these cell surface molecules on the adhesive properties of these cells. The observation that anti-beta chain mAb strongly inhibited migration, chemotaxis, adhesion and phagocytosis of monocytic cells indicates a major role for LFA-1 family antigens in monocyte functions. Detailed analysis with a panel of anti-alpha chain antibodies demonstrated that both p150,95 and LFA-1 mediate random migration whereas in contrast, p150,95 and CR3 were shown to be involved in the directed migration of monocytes to f-Met-Leu-Phe. Furthermore, adhesion of monocytes to plastic surfaces or monolayers of endothelial cells as well as phagocytosis of latex particles was mediated by p150,95. The results demonstrate that, in spite of its relative low expression, the p150,95 glycoprotein is a major adhesion-associated molecule expressed by human monocytic cells.

The response of selected human B cell lines to B cell growth and differentiation factors

Fifteen human B cell lines were tested for their ability to respond to B cell growth and differentiation factors present in phytohemagglutinin-conditioned medium. Five lines responded significantly: CESS showed an increase in IgG production only, HFB1 and BALM1 showed an increase in proliferation only and L4 and BALM4 showed an increase in both IgG production and proliferation. When four of the responding lines (CESS, HFB1, L4 and BALM4) were cultured with human recombinant-derived interleukin 1, interleukin 2, interleukin 4 or interferon-gamma no significant response was seen. CESS, L4 and BALM4 all increased IgG production in response to partially purified B cell growth factor (Cellular Products, Inc., Sera-Lab., Crawley Down, GB) and B cell differentiation factor-containing supernatant from the T24 bladder carcinoma cell line. HFB1, L4 and BALM4 all showed increased tritiated thymidine incorporation in response to purified B cell growth factor but not in response to B cell differentiation factor-containing supernatant. These lines may prove useful in the study of B cell growth and differentiation factors and their receptors.

Distribution and functional analysis of a 120- to 130-kDa T-cell surface antigen

A monoclonal antibody (mAb), SPV-L14, was raised that detected a human T-cell surface antigen with a molecular weight (MW) of 120 kDa on resting and phytohemagglutinin-activated peripheral blood T lymphocytes (PBL). An additional band with a MW of 130 kDa could be precipitated with variable intensities from thymocytes, neoplastic T cells, and CD4+- or CD8+ T-cell clones. Based on their reactivity with SPV-L14 and a mAb directed against CD3, four subpopulations of CD2+ lymphocytes could be detected and their existence was confirmed at the clonal level. The majority (95%) of the CD3+ cells were SPV-L14+, whereas 5% were CD3+, SPV-L14-. Among cloned cell lines CD3-,SPV-L14- and CD3-,SPV-L14+ cells were found to exist. The CD3-,SPV-L14- and CD3-,SPV-L14+ clones were shown to have NK cell activity, indicating that the 120- to 130-kDa antigen is expressed heterogeneously on CD3- NK cell clones. In addition, neoplastic T cells representing these four subpopulations were shown to exist. Although the tissue distribution and the MW of the SPV-L14 target antigen strongly suggest that SPV-L14 reacts with an epitope on CD6, the SPV-L14 mAb did not react with resting or activated B cells or with malignant B cells. Blocking studies showed that SPV-L14 inhibited the proliferative response of PBL, induced by anti-CD3 mAb, but that SPV-L14 did not affect the proliferation induced by phytohemagglutinin. These results suggest that the 120- to 130-kDa MW antigen is associated with T-cell proliferation, depending on the mode of activation.

Sensitive and quantitative determination of monocyte adherence

A new sensitive and highly reproducible one-step ELISA is described to quantitatively determine the adherent capacity of monocytes and related cell lines. Cells were labelled with a monoclonal antibody/peroxidase conjugate which did not affect the adhesive properties of these cells. The labelled cells were allowed to adhere for 1 h and subsequently stained by the addition of substrate. The results demonstrate that there is a good correlation between the number of peroxidase-labelled adherent cells and the absorbance measured at 450 nm. Furthermore the assay permits the use of very low cell numbers since adherent cells could be measured efficiently at a level of only 100-500 cells/well. The method may be very useful in the selection of hybridomas that secrete antibodies which inhibit adherence of cells. In addition it can be applied to study the adhesive properties of any cell type, provided that appropriate monoclonal antibodies are available.

T cell clones which share T cell receptor epitopes differ in phenotype, function and specificity

Recently, we described a monoclonal antibody (3D6) that reacts with the T cell receptor (Ti) of the T leukemic cell line HPB-ALL and that cross-reacts with 2-10% of the T cells of normal healthy individuals. In this study we report the establishment of T cell clones that are 3D6+ but that differ in function and phenotype. These clones were established according to two different protocols: T cells of donor HY (10% 3D6+) were stimulated with the Epstein-Barr virus-transformed cell line JY. The proliferating 3D6+ T cells were enriched using a rosetting technique and cloned. T cells of donor HY were stimulated with the 3D6 antibody and subsequently expanded in recombinant interleukin 2-containing medium. This yielded 70% 3D6+ T cells which after activation with either Daudi cells or with TT in the presence of autologous non-T cells, followed by cloning, resulted in antigen-specific 3D6+ T cell clones. The 3D6+ T cell clones were also tested on their reactivity with 4 other monoclonal antibodies (1C1, 1C2, 2D4, 65) specific for the Ti of HPB-ALL. The antibodies 1C1 and 1C2 reacted with all 3D6+ T cell clones and recognize probably the same epitope as 3D6. The antibodies 2D4 and 65 reacted with two mutually exclusive subsets of T cell clones. All the anti-Ti antibodies reacted with functional epitopes, since they were able to block the function of the T cell clones. The specificity of the clones was investigated by blocking studies using monoclonal antibodies specific for different major histocompatibility complex antigens. No correlation was found between the expression of the different Ti epitopes and the specificity, the CD4/CD8 phenotype or function of the clones.

Isolation and characterization of a human interleukin cDNA clone, homologous to mouse B-cell stimulatory factor 1, that expresses B-cell- and T-cell-stimulating activities

A cDNA sequence coding for a human interleukin has been isolated from a concanavalin A-activated human T-cell cDNA library based on homology with a mouse interleukin cDNA that expresses B-cell stimulatory factor 1 (BSF-1) activity and T-cell- and mast-cell-stimulating activities. The human cDNA contains a single open reading frame encoding a protein of 153 amino acid residues including a putative signal peptide. Amino acid sequences of the mouse and human polypeptides, deduced from their cDNAs, share extensive homology with the exception of about 40 amino acid residues near the middle portion, which share little homology. Supernatant of COS-7 monkey cells transfected with the human cDNA clone stimulated proliferation of human helper T-cell clones and of anti-IgM-activated human B cells, two properties of mouse BSF-1 on mouse cells. These results indicate that this human cDNA clone encodes a protein structurally and functionally homologous to mouse BSF-1.

Biochemical and functional characteristics of the human leukocyte membrane antigen family LFA-1, Mo-1 and p150,95

The human leukocyte function-associated (LFA-1) antigen, the monocyte differentiation antigen Mo-1 which is characterized as the C3bi receptor and the glycoprotein p150,95 are characterized biochemically. Immunoprecipitations carried out with 6 different monoclonal antibodies (mAb) against LFA-1 indicated that four mAb (SPV-L1, SPV-L5, SPV-L7 and SPV-L11) were directed against the alpha chain, whereas mAb CLB54 and MHM-23 were found to react with the common beta chain of LFA-1, Mo-1 and p150,95. LFA-1 and Mo-1 expressed on KG-1 cells or lymphocytes, monocytes and granulocytes from one donor were homogeneous. Interestingly the alpha chain of p150,95 showed heterogeneity. The molecular weight of the alpha chain expressed on monocytes was consistently higher than that of the alpha chain on granulocytes. The beta subunits of LFA-1 and Mo-1 (as detected by mAb Bear-1) are not only similar in molecular weight and isoelectric focusing patterns, but it is demonstrated here that they are also identically glycosylated and have similar protein backbones as judged by tryptic peptide mapping. In spite of their structural similarities. LFA-1 and Mo-1 differ completely in some of their biological functions. Anti-LFA-1 mAb strongly inhibited monocyte-dependent T cell proliferation induced by tetanus toxoid or Helix pomatia hemocyanin and pokeweed mitogen-driven specific antibody production in vitro, whereas the anti-Mo-1 antibody Bear-1 was ineffective. These results suggest that the differences in these biological functions of LFA-1 and Mo-1 may be related to their different alpha subunits, which may recognize specific counter structures.

Jejunal mucosal DNA content and maturation. Inverse relation to serum gastrin levels in suckling and weanling rats

Although pentagastrin has a tropic action on intestinal mucosa in suckling rat pups, and at weaning a rise in gastrin levels coincides with maturation of the intestinal mucosa, direct correlations of serum gastrin levels and intestinal maturation have yet to be made. Ten-day-old rats were subjected either to antrectomy to produce a 43% decrease in serum gastrin levels or to fundectomy to produce a 319% increase over gastrin levels in rumenectomized or normal animals. These changes were not associated with tropic or adaptive changes in jejunal or colonic mucosa as determined by jejunal and colonic DNA content, jejunal sucrase activity, jejunal villous height, or crypt depths in jejunum and colon at the beginning (day 15), middle (day 21), or end (day 27) of the weaning period. To the contrary, an inverse relation was found between serum gastrin levels and both jejunal mucosal DNA content and sucrase activity as an index of maturation.

Antigen-specific cytotoxic T cell and antigen-specific proliferating T cell clones can be induced to cytolytic activity by monoclonal antibodies against T3

T3 is a human differentiation antigen expressed exclusively on mature T cells. In this study it is shown that anti-T3 monoclonal antibodies, in addition to their capacity to induce T cells to proliferate, are able to induce antigen-specific cytotoxic T lymphocyte clones to mediate antigen nonspecific cytotoxic activity. It is furthermore shown that anti-T3 reagents are able to trigger lytic activity in T cell clones characterized as noncytotoxic antigen-specific proliferating T cells. The data presented indicate that perturbation of T3 can trigger the lytic machinery in cytolytic as well as noncytolytic T cell clones.

Induction of IL-2 production, IL-2 receptor expression and proliferation of T3- T-PLL cells by phorbol ester

Leukemic T cells from the peripheral blood of a patient with T-prolymphocytic leukemia (T-PLL) were investigated for their potential to differentiate in vitro upon exposure to 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The T-PLL cells, identified as typical PLL cells by nuclear morphology, were typed as E+slg-OKT1+3-4+6-8-11+ cells lacking reactivity with OKI-1 or OKM-1. In addition, between 3% and 10% of the cells reacted with monoclonal antibodies against T10. In contrast to normal T cells, the T-PLL cells could not be induced to proliferate by mitogenic lectins or alloantigens in the presence or absence of human interleukin-1 (IL-1), interleukin-2(IL-2) or allogeneic monocytes and did not produce IL-2. They also failed to proliferate in response to TPA or TPA in the presence of phytohemagglutinin (PHA), but under these conditions T-PLL cells secreted high levels of IL-2 activity. Incubation in the presence of PHA + TPA or TPA for 48 h induced T-PLL cells to become blasts exhibiting enhanced protein synthesis, and induced a 10-fold increase in the percentage of cells reactive with monoclonal antibodies against T10. At the same time, about 15% of the cells developed receptors for IL-2 as monitored by their reactivity with anti-Tac monoclonal antibody. Washing of these T-PLL cells to remove TPA resulted in the induction of proliferation upon subsequent culture in the presence of IL-2 or in medium only. Since proliferating T-PLL cells still failed to express T3 antigens, it was concluded that these leukemic cells represent a T-cell differentiation stage or a T-cell subset which can be activated via a T3-independent pathway.

Serum-free medium for generation and propagation of functional human cytotoxic and helper T cell clones

A serum-free lymphocyte culture medium is described in which serum is replaced by bovine serum albumin, transferrin, insulin, ethanolamine and a mixture of saturated and unsaturated fatty acids (linoleic acid, oleic acid and palmitic acid). In this serum-free medium proliferative and cytotoxic responses induced in mixed lymphocyte culture were comparable with those obtained in medium containing serum. Antigen-specific cytotoxic and helper T cells were isolated and could be propagated in serum-free medium without loss of function.

HLA-DC antigens can serve as recognition elements for human cytotoxic T lymphocytes

The specificity of four cytotoxic T lymphocyte (CTL) clones which recognize class II major histocompatibility complex (MHC) antigens was analyzed. All clones recognized antigens associated with the serologically defined HLA-DRw6 specificity. The activity of two of these clones, JR-2-2 and JR-2-10, could be inhibited by a monoclonal antibody Q 5/13 specific for a monomorphic determinant present on HLA-DR. In contrast, the activity of the two other CTL clones, JR-2-19 and JR-2-26, was not blocked by Q 5/13, but by a new monoclonal reagent, SPV-L3. This latter monoclonal antibody precipitated a two-chain structure of 28 kDa and 33 kDa and reacts with a monomorphic determinant. The molecular weight of the polypeptides precipitated with SPV-L3 was slightly less than those precipitated with a HLA-DR-specific monoclonal reagent. In addition two-dimensional gel electrophoresis showed that the antigen precipitated by SPV-L3 differed in charge from those precipitated with the anti-HLA-DR antibody. These results indicate that SPV-L3 recognizes a class II MHC product different from HLA-DR. This observation was confirmed by partial amino acid sequence analysis of the two chains which revealed that the molecule precipitated by SPV-L3 is homologous to HLA-DC/DS molecules. Therefore this report provides the first evidence that human cytotoxic T cells can recognize HLA-DC/DS antigens.

Growth and metabolic alterations after submandibular sialadenectomy in male mice

Because the submandibular salivary glands of male mice are rich in growth factors such as epidermal growth factor and nerve growth factor, and because there are sporadic reports of sialadenectomized mice showing growth retardation and endocrine abnormalities, we studied oxidative metabolism and fertility after submandibular sialadenectomy. Despite similar intake of food, male mice (n = 60) deprived of submandibular saliva, either by duct ligation or gland excision, initially weighed 12-13% less than the sham controls and had a slower rate of growth (P less than 0.001). After 5 mo, mice with duct ligation caught up with the sham-operated mice, but the differences compared with submandibular-sialadenectomized mice were still apparent at 32 wk (P less than 0.001). The mean respiratory quotient of submandibular-sialadenectomized and duct-ligated mice was 0.71 instead of 0.88 as in the shams at 10, 20, and 30 wk after operation (P less than 0.01). No effect on fecundity was observed in either male or female mice following submandibular sialadenectomy.