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Due to the unknown etiology of RA, specific treatment is not available. Recently, in a double-blinded, placebo-controlled clinical trial, in vivo blockade of TNF-alpha by a single infusion of a chimeric TNF-alpha-blocking mAb, cA2, has proven to be highly effective in the treatment of RA. In parallel to this trial, we tested the consequences of cA2 infusion in ex vivo and in vitro experiments. In this paper, we describe an increase in CD4+ and CD8+ T lymphocyte counts on day 1 and a marked decrease in monocyte counts preferentially on day 7 after cA2 treatment, without major changes in B lymphocyte or NK cell counts. In addition, we found an increased responsiveness of PBMC to CD28 mAb/PMA, but not to CD3 mAb, superantigen staphylococcus enterotoxin B, or PHA on day 1 after infusion. The increase in DNA synthesis of PBMC was paralleled by increased IL-2 mRNA and IL-4 mRNA expression and IL-2 protein secretion in culture supernatants after in vitro stimulation of PBMC with CD28 mAb/PMA. In PBMC, we did not find any significant changes in mRNA or protein expression of CD28 Ag or CD28 ligands, B7-1 and B7-2. Serum concentrations of IL-1 beta, IL-6, and soluble CD14 were significantly diminished after in vivo TNF-alpha blockade. We did not see relevant changes in granulocyte function in vitro after cA2 infusion. Finally, we observed a statistically significant decrease in slCAM-1 molecules in the serum of patients treated with verum compared with that in the serum of subjects given placebo. This change in slCAM-1 concentration was evident on days 1 and 7 after the infusion of 10 mg/kg cA2, whereas it occurred only on day 7 in the serum of patients treated with the low dose (1 mg/kg) of cA2.

In a previous report, peripheral blood mononuclear T cells from a patient with T-chronic lymphocytic leukemia (T-CLL) were shown to bear receptors for the Fc portion of IgG (T gamma). Moreover, the ability of these cells to rosette with sheep erythrocytes was strongly inhibited by a preincubation of the cells with theophylline. These data indicated that they represent a highly purified subpopulation of Fc-IgG receptor-positive, low-affinity rosetting cells with in vitro suppressor activity on lectin-induced proliferation of normal lymphocytes. They also were reactive in antibody-dependent cell-mediated cytotoxicity but had no reactivity in natural killer cell assays. These cells were studied in this report with several heteroantisera and monoclonal antibodies. Results indicate that these T-CLL cells express a T cell antigenic pattern (OKT-3+) and the majority are Ia positive. They also react with the OKT-8 reagent (a reagent detecting the subset of T cells that contains the cytotoxic/suppressor cells), whereas they are negative with OKT-4 (which reacts with the subset of T cells that contains helper cells) and OKT-6 (thymocyte) antibodies. Heteroantisera also support the results obtained with monoclonal reagents. Despite some recent evidence showing that a high percentage of T gamma cells may belong to the monocyte-myeloid lineage, these T-CLL cells were negative with OKM-1, a monoclonal antibody reported to detect a monomyeloid antigen. These results suggest that a distinct subpopulation of suppressor T cells can be identified by membrane-marker phenotyping.

The nature of the cell population involved in lymphocyte mediated cytotoxicity to baby-hamster-kidney (BHK-21) target cells persistently infected with rubella virus was investigated by a 51Cr-release microassay. After depletion of the T cell population with an antiserum to human0thymus-lymphoid tissue antigen (HTLA), the purified B cell population showed a decrease in E-rosette formation (9.0 +/- 2.2% compared to 69.6 +/- 9.1% before treatment) and an insignificant degree of cytotoxic activity against rubella-infected target cells (specific immune release of 51Cr was 0.9 +/- 2.6% compared to 24.2 +/- 3.8 before treatment). A purified T cell population, prepared by depletion of B cells with an anti-human immunoglobulin serum and complement, was found to show no alteration in E-rosette formation (85.2 +/- 6.2%) or cytotoxicity (30.3 +/- 4.4% SIR) but showed decreased EA- and EAC-rosette formation (2.7 +/- 1.5% and 10.5 +/- 3.2%, respectively, compared to 19.4 +/- 2.9% and 28.0 +/- 4.1% before treatment). A monocyte-depleted population prepared by removal of the plastic adherent mononuclear cells showed no significant alteration of rosette formation or cytotoxicity. These experiments suggest that the predominant lymphoid population responsible for direct cell-mediated cytotoxicity to virus infected target cells in the 51Cr-release microassay appears to be effected by a thymus-dependent lymphocyte population.

Analysis of a murine model of schistosomiasis revealed that both the thymus (T)- and bursa (B)-derived compartments of the immune system are modified during acute infection. The functional capacity of T and B lymphocytes to respond to mitogenic stimuli and the humoral response to thymus-dependent (SRBC) and thymus-independent (DNP-Ficoll) antigens are severely depressed. In addition, it was found that suppressor cells capable of inhibiting the response of normal lymphocytes to SRBC arise during acute infection. Although the splenic frequency of T (theta) and B (Ig+) cells remained constant during chronic infection, quantitative changes were detected in each population. In the T cell pool there was a decrease in the percentage of Ly-1+ cells and a concomitant increase in Ly-1+, 2+, 3+, cells, whereas the B cell pool showed a progressive loss of complement receptor-bearing lymphocytes, which apparently was the result of inactivation of surface complement receptor by a serum factor specifically found in infected mice. Characterization of the serum factor strongly suggests it is an immune complex. Thus, it appears that both suppressor cells and immune complexes contribute to changes noted in the immune system during acute schistosomiasis. Additional studies carried out in mice after unisexual infection revealed that egg production is not a necessary prerequisite for several of the immunologic phenomena associated with acute schistosomiasis.

Human peripheral blood lymphocytes from an HLA-Dw1,3 individual were primed in vitro with influenza A virus (A/Texas/1-77/x-49) and subsequently cloned by limiting dilution in TCGF. Of the 96 TLCs originally obtained, nine were characterized in detail. TLCs were antigen specific, responding to influenza A virus, not to influenza B, TGAL, GAT, tetanus toxoid, or KLH, and only when antigen was presented by cells unable to form rosettes with AET-treated SRBC. Presentation of antigen by unseparated PBL often resulted in significant "back stimulation," probably via production of growth factors. The MHC requirements for the induction of TLC proliferation were analyzed. Of four representative clones analyzed, three required Dw1;DR1 compatibility for successful presentation of viral antigens by a panel of antigen-presenting cells. In contrast, one TLC showed an unusual pattern of response that could not be correlated to a particular HLA haplotype. Monoclonal anti-T cell antibody analysis of the surface phenotype of two TLCs maintained in continuous culture for 5 mo indicated that they were OKT3+, 4+, and 8-, consistent with an inducer/helper phenotype. To confirm the clonal nature of TLCs, data on the functional properties of TLC subclones are also presented.

The association between multiple sclerosis (MS) and HLA-DR2 suggests that the disease may be associated with an aberrant immune response, likely directed against an antigen of either viral or host origin. We have used measles virus-specific T cell clones derived from a patient with MS to study genetic restriction patterns of antigen presentation by macrophage-enriched (E-) populations. Twenty-two clones proliferated in response to measles-infected Vero cells but not to mumps-infected or uninfected Veros. E- cells from both the autologous subject and her healthy, measles nonresponder identical twin were capable of presenting antigen to all clones. Studies with E- cells obtained from a panel of cell donors demonstrated clones which recognized antigen in association with D2/DR2, DR4, subgroups of DR4, and SB3. Three clones recognized antigen only in association with the autologous or twin's cells, but not with other sets of HLA-matched E-cells obtained from healthy donors or from other patients with MS. These studies indicate that the differing responses to measles virus demonstrated by these two identical twins are not explained by alterations in the interactions between antigen-presenting cells and T cells. Furthermore, at the clonal level, no preferential role is seen for HLA-DR2 as the restricting element for presentation of measles virus to these clones.

Activation of murine B lymphocytes in a splenocyte stimulator population with affinity-purified goat anti-mouse IgD (G alpha M delta) antibody was previously shown by this laboratory to enhance the presentation of strongly stimulatory major histocompatibility complex (MHC) and minor lymphocyte-stimulating (Mlsa,d) determinants in a primary mixed lymphocyte reaction. In the present study, the G alpha M delta treatment of murine splenocytes was employed to enhance the detection of the weakly stimulatory non-MHC Mlsc determinant in order to study the role the MHC might play as a restricting element for the recognition of these minor antigens in a primary mixed lymphocyte reaction. Indeed, enhanced T cell proliferation to Mlsc determinants presented on G alpha M delta-treated splenocytes was observed when the responder and activated H-2-compatible stimulator cell shared certain MHC haplotypes. High responsiveness was associated with the H-2a,k,j,p haplotypes, intermediate responsiveness was associated with the H-2f,g haplotypes and low responsiveness was associated with the H-2b,s haplotypes. (Low X high responder)F1 T cells preferentially responded to the Mlsc determinants presented on G alpha M delta-treated stimulator cells of the F1 or parental high responder H-2 haplotype. When mitomycin C instead of irradiation was used to inactivate normal (non-IgD-treated) splenocytes, a similar preferential response of T cells to Mlsc determinants presented on stimulator cells of a high responder H-2 haplotype was also observed. The inability of G alpha M delta-treated splenocytes of the low responder haplotype to elicit substantial levels of T cell proliferation across an Mlsc difference could not be attributed to the failure of these stimulator cells to become activated by the anti-Ig antibody. In addition, co-culture experiments could not identify the poor T cell response to Mlsc determinants presented on certain MHC haplotypes as being caused by the induction of nonspecific suppressor cells. Presentation of Mlsc determinants caused by transgene product complementation was detectable in F1 mice derived by crossing one parent that had the Mlsc non-MHC genes and a poorly permissive H-2 haplotype with a parent that expressed a permissive H-2 haplotype but lacked the Mlsc non-MHC genes.(ABSTRACT TRUNCATED AT 400 WORDS)

Cloned human T lymphocytes induced with influenza A virus (A/Texas/1/77) and maintained in continuous culture with T cell growth factor were assayed for helper function in the in vitro production of anti-influenza antibody. Helper function mediated by both cloned helper T cells and normal peripheral blood lymphocytes was highly antigen dose-dependent, requiring lower concentrations than that necessary to induce blastogenesis. Optimal help was observed with 1 X 10(2) cloned T cells per culture, whereas excess helper cells inhibited the response. After culture with influenza A virus-induced cloned helper T cells, the antibodies formed were directed against influenza A and not B virus. Furthermore, the cloned helper T cells despite being specific for matrix protein collaborated in the production of predominantly anti-hemagglutinin antibody, suggesting associative recognition of the two discrete antigens. Cellular interactions between cloned helper cells from an HLA-Dw1,3 DR1,3 individual and erythrocyte rosette-negative cells required HLA-Dw1; DR1 compatibility for the production of specific antibody. This was confirmed by using subclones. Finally, it was observed that supernatants of the cloned helper T cells contained functional activity capable of replacing the parent cells in the production of anti-influenza A virus antibody.

Human T lymphocyte clones (TLC) specific for type A (A/Texas/1/77) influenza virus and maintained in continuous culture with T cell growth factor, were analyzed to define the cellular specificity pattern of virus recognition. A panel of TLC were stimulated with strains of serologically characterized type A influenza subtypes. Five TLC recognized all the viral subtypes; the remaining clones recognized only subtypes that shared serologically defined determinants with the immunizing subtype. In addition, the 11 TLC were analyzed for their fine antigenic specificity by using the purified viral components hemagglutinin (HA), neuraminidase (NA), matrix protein (MP), and nucleoprotein (NP). Five TLC proliferated in response to NA, four to MP, one to HA, and one to NP. None of the clones responded to the unrelated B strain influenza virus, B/Singapore. Furthermore, the fine specificity of an MP-reactive TLC was confirmed by subcloning.

The restoration of sensitivity to azathioprine of athymic (nu/nu) mouse splenic rosette-forming cells (RFC) has been used by others to assay thymic hormone. These previous studies have led to the conclusion that a major factor in the development of autoimmunity in New Zealand (NZ) mice and patients with systemic lupus erythematosus (SLE) is the premature loss of thymic hormone. We have studied the mouse rosette assay and find that poly A-Poly U and single stranded DNA, in addition to thymosin, restored azathioprine sensitivity to nu/nu RFC. Thus, other substances may mimic thymic hormone, perhaps via the cyclic AMP system. Furthermore, antibodies to T cells were found to interfere with the assay. Sera from old NZ mice which contain naturally occurring thymocytotoxic antibodies (NTA) failed to restore azathioprine sensitivity. Small quantities of NTA prevented normal sera from functioning in the assay. We conclude that the role of thymic hormone(s) in the development of autoimmunity in NZ mice and patients with SLE must be completely reevaluated.

With anti-Ly antisera and complement it has been possible to demonstrate that cytotoxic effector cells generated in vitro against allogeneic cells carry the alloantigen Ly-5 and Ly-6. The studies show that antisera directed against the Ly-6 antigens, together with complement, eliminate essentially all of the killer cells, of the appropriate strain, while killing only 50 to 60% of Thy-1+ cells. Anti-Ly-5 antsera and complement lysed 55 to 65% of Thy-1+ cells and killed a significant portion, but not all, of the cytotoxic cells. The later finding was investigated in more detail since it suggested a degree of heterogeneity within the killer cell subpopulation. However, the data did not support that conclusion, at least for allogeneic killer cells.

The F(ab')2 fragment of rabbit anti-human F(ab')2 antibodies covalently linked to polyacrylamide beads (anti-Ig beads) acts as a polyclonal mitogen for human B cells in whole peripheral blood mononuclear cells (PBM) or tonsil cells. Activation, measured by the rate of DNA synthesis, is the result of an interaction between the anti-Ig beads and membrane immunoglobulin found on B cells. Excess soluble human F(ab')2 blocks activation with anti-Ig beads. Immunospecifically purified antibodies against IgM or IgD bound to beads activate lymphocytes. Also soluble anti-IgM or anti-IgD can block activation with insolubilized anti-IgM or anti-IgD, respectively, by modulating membrane immunoglobulin. Irrelevant rabbit antihapten antibodies bound to beads failed to activate PBM or tonsil cells. Anti-Ig beads act independently of T cells. The anti-Ig beads lead to activation of B cells without further maturation to polyclonal immunoglobulin secretion.

We studied the effects of xenoantiserum to human nonpolymorphic Ia-like antigens upon in vitro antigen-specific T cell proliferative responses in unfractionated PBL populations and at the monoclonal level. Our findings suggest that the xenoantiserum, although it inhibits the antigen-specific response of unfractionated PBL and allospecific T cell clones, does not inhibit the proliferative response to cloned influenza virus immune human T lymphocytes, and therefore may be mediating inhibition by dual mechanisms: direct inhibition of alloantigen recognition and induction of nonspecific suppression. Kinetic differences may explain these phenomena. In cocultivation experiments with a virus-specific clone, the RaIa antiserum appears to induce an OKT3+,8+,4-, radiosensitive regulatory subset of lymphocytes. When adoptively transferred, these induced cells inhibit the TLC response in an antigen-nonspecific and genetically nonrestricted manner. We discuss the various modes and levels of inhibition of antigen-specific proliferation by anti-Ia antisera and their multiple activities.

Antigen-specific helper factor was induced in vitro from lymphoid cells of monkeys and mice by using an antigen derived from Streptococcus mutans. Helper activity was removed from supernatants of monkey cells by affinity chromatography on Sepharose 4B insolubilized antibodies specific for human beta 2-microglobulin (H beta 2M) prepared in chicken, rabbit and rat, and an insolubilized monoclonal mouse anti-H beta 2M antibody-bound monkey helper factor activity. However, guinea pig antibody to human beta 2M was inactive. In parallel studies, the pattern of absorption of mouse helper factor (HF) was different from that of the monkey in that insolubilized guinea pig anti-H beta 2M bound helper factor, whereas rabbit and monoclonal anti-H beta 2M failed to do so. Although these findings were not compatible with an intact beta 2M chain being present in helper factor, they may imply a cross-reactivity of beta 2M with a "constant region" of helper factor that may share common sequences with beta 2M. This may suggest that factor genes have evolved from the same ancestral genes as beta 2M.