The role of suppressor factors in the regulation of immune responses by ultraviolet radiation-induced suppressor T lymphocytes. III. Isolation of a suppressor factor with the B16G monoclonal antibody

Production of a suppressor factor by CD8+ lymphocytes activated by mycobacterial components

The lipid component present in high-molecular-mass fractions with molecular masses of greater than 200 kDa derived from Mycobacterium tuberculosis extracts passaged through Sephacryl S.200 columns activate CD8+ lymphocytes to suppress lymphocyte blastogenesis. Suppression is mediated by the release of suppressor molecules by these CD8+ lymphocytes. Release of suppressor molecules occurs as early as 2 h following pulsing with the high-molecular-mass mycobacterial components and is maximal at 24 h, after which their release declines rapidly. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting indicates that the active components are carbohydrate moieties with approximate molecular masses of 122 to 148 kDa. Our results suggest a mechanism of interaction between mycobacteria and host mononuclear cells such that mycobacterial lipids, once exposed, activate CD8+ suppressor lymphocytes. Activation of these lymphocytes results in the release of carbohydrate-containing molecules that ultimately inhibit the blastogenesis of other lymphocytes.

Suppressor cells and soluble factors from the spleens of UV-irradiated mice

Several indices of splenic reactivity were measured daily after ultraviolet (UV) irradiation of mice. Spleen weight increased to a maximum after 5 days. Suppressor cell activity, manifested in various assays, peaked slightly earlier. The ability of passively transferred spleen cells to suppress the induction of contact hypersensitivity (CHS) was maximal after 4 days, as was the production of soluble suppressor factors in culture. The factors were detected by suppression of CHS in vivo and leucocyte adherence inhibition (LAI) in vitro. These assays appeared to detect different factors: an I-J- factor active in CHS assays and an I-J+ factor active in LAI assays. The latter factor required CD4-, CD8+ lymphocytes for its production.

Distinctive molecular markers and biological activities in two tumour-specific murine T suppressor factors

Murine suppressor factors (SF) in tumour-bearer serum (TBS) and tumour-bearer spleen cell culture supernatants (SCCS) were compared with regard to their molecular markers, cellular requirements and suppressive activities. Suppressor factors in SCCS bear the idiotype I-J, and markers recognized by B16G and anti-lipomodulin antibodies require Ly2+ I-J+ cells for their production and cells of the same phenotypes, for suppression to be manifested in leucocyte adherence inhibition (LAI) assays, are not immunoglobulin (Igh)-restricted and are active in both the afferent and efferent phases of the immune response. Suppressor factors from TBS resemble those from SCCS with regard to idiotype, I-J and lipomodulin-like markers, but in contrast, do not bind to B16G antibody, require Ly2+ but not I-J+ cells for suppression to be manifested in LAI assays, are Igh-restricted, and suppress delayed-type hypersensitivity (DTH) reactions only when injected in the afferent phase. These results show that the SF from the different sources in tumour-bearing mice are not identical; they may be different parts of a suppressor cascade, or they may belong to entirely separate suppressor cascades.