Antigen-specific suppression of anti-influenza antibody production in man. Possible role of a membrane-antigen complex

Specificity and in vitro transfer of the immunosuppressive effect of detergent-disrupted influenza virus vaccine

Primed murine splenocytes give an in vitro antibody response to influenza whole virus vaccine (WVV), as measured by enzyme immunoassay (EIA). When subunit vaccine (SV) of either influenza A or influenza B virus was added to in vitro splenocyte cultures stimulated with WVV, the EIA antibody response to homologous WVV was reduced. This reduction in antibody response was observed when SV was prepared using zwitterionic detergent (empigen BB), non-ionic detergent (triton-X-100) or cationic detergent cetyl-trimethyl ammonium bromide (CTAB); it was found to be effected only by SV of strains of the same virus subtype--when SVs prepared from a heterotypic (H3N2) strain, an H1N1 strain and an influenza B strain were added to splenocyte cultures in the presence of WVV. When splenocytes from immunologically naive mice, exposed in vitro to SV, were transferred to secondary cultures of primed splenocytes, the antibody response to WVV in the secondary cultures was also reduced. Mechanisms that may suppress the in vitro antibody response are discussed.

High dose suppression of human anti-influenza A virus responses using T cell clones

Human T cells exposed to high concentrations of influenza A virus cause specific suppression of the in vitro antibody response to the virus, but the phenomenon does not require viable T cells. In order to investigate the mechanism of this form of suppression, IL-2-dependent T cell clones of helper phenotype (CD4+, HLA-DR+, IL-2R+) were prepared with specificity for influenza A (Mem/Bel) and B (B HK) viruses and the non-crossreacting antigen purified protein derivative (PPD). When pulsed with high dose Mem/Bel virus, all three clones transferred suppression equally well to effector cultures of syngeneic or allogeneic E+ and E- cells stimulated with an immunogenic dose of the same virus. Thus, although suppression was specific at the level of expression, the induction phase was non-specific and non-major histocompatibility complex (MHC) restricted and did not involve interaction of antigen with the T cell receptor. HLA-DR, CD3 and CD8 determinants were excluded as the binding site for the virus by two-colour immunofluorescent staining and flow cytometric analysis. The concentrations of antigen required for high dose suppression inhibited antigen-specific proliferation by the clones; on the other hand, they remained partially sensitive to IL-2 and could still release gamma-interferon. These findings suggest that this phenomenon is distinct from conventional antigen-specific suppression mediated by CD8 T cells, but may play a biologically important role in regulating immune responses at least to viral antigens.

Antigen-specific suppression of human antibody responses by allogeneic T cells. II. Cell interactions involved in the generation of suppression

Specific antibody responses to influenza virus were obtained in vitro from human blood mononuclear cells (PBMC). Antibody production in these cultures was profoundly suppressed by the addition of allogeneic T cells with the surface phenotype Leu2a+ (CD8+), Leu8-. Suppression by allogeneic T suppressor (Ts) cells required interactions only between T-depleted B (E-) cells and allogeneic Leu2a+. No evidence was obtained for T-T cell interactions, or for Ts inducer cells similar to those described for nonspecific antibody responses to pokeweed mitogen. Moreover, allogeneic E+, or allogeneic Leu2a+ cells were able to suppress specific antibody responses by E- cells when help was provided by T cell-replacing factor showing that the target of suppression was the responding E- cells, and not T helper cells. In contrast to allogeneic T cells, allogeneic E- cells did not suppress antibody production when added to cultures of unfractionated PBMC (E- + E+). That is, Ts cells activated to allogeneic E- were unable to suppress antibody production by the syngeneic E- cells present in the same culture tube. This result shows that alloactivated Ts cells were specific for the allogeneic E- target cells, and that suppression was not mediated by nonspecific allogeneic effects. Allogeneic Ts cells therefore differ from Ts cells in pokeweed mitogen responses by their specificity, and by their activation in the absence of Ts inducer cells.