Comparison of T suppressor factors from tumour-bearing mice and mice immunized with a monoclonal anti-idiotypic antibody

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.

Effects of anti-idiotype vaccine on tumour growth and on production of soluble factors modulating cell-mediated immunity in vitro

The previous observation, that single i.p. doses of a monoclonal anti-idiotypic antibody (MAIA) injected into BALB/c mice induced suppressor factors, was extended to multiple i.v. doses. These induced enhancing factors, which were produced in spleen cell cultures, required L3T4+ cells for their formation, lacked the IJ marker, and bound to anti-immunoglobulin, showing them to be antibodies. Selective immunoabsorption demonstrated two separate enhancing antibodies; both bound to MAIA but they had different affinities for specific and non-specific tumour antigens. Subsequently, single and multiple MAIA doses were tested in vivo for their effects on tumour growth. The single doses had variable effects depending on time of administration, and these effects were tumour-specific; the multiple doses strongly inhibited tumour growth when given before tumour challenge, but also had non-specific effects on another tumour as anticipated from the in vitro results.