Understanding suppressor cells: where have we gone wrong?

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.