TRF requirements for in vitro PFC responses to SRBC and R36a. I. TRF is distinct from IL 2 but indistinguishable from polyclonal BCSF.
In vitro PFC responses to the thymus-independent (TI) antigen Streptococcus pneumoniae R36a require T cell replacing factor(s) (TRF). This requirement for TRF is as significant as for the thymus-dependent (TD) antigen SRBC. TRF is shown to be distinct from IL 2 by the following observations: 1) culture supernatants from the cloned T cell line L2, collected over an 8-day period after allogeneic stimulation, transiently contain IL 2 activity but maintain high levels of TRF activity throughout 192 hr; 2) L2V, a variant subclone of L2, produces much higher levels of TRF activity than the parental line but no detectable IL 2 activity; 3) the addition of IL2+, TRF- supernatants from the T cell hybridoma FS6-14.13 does not affect the L2V SF-driven PFC responses to R36a or SRBC; and 4) the addition of contaminating T cells to cultures containing T cell-depleted spleen cells, L2V SF, and antigen does not affect the PFC response. TRF does appear to be indistinguishable from polyclonal B cell stimulating factor (BCSF), which stimulates polyclonal PFC responses in the absence of antigen, mitogen, or anti-Ig. The TRF and BCSF activities of L2V SF could not be separated by ion-exchange, hydrophobic-interaction, and gel-filtration chromatography. TRF and BCSF have an apparent m.w. of approximately 40,000.
D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D000955:Antigens, T-Independent / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D006133:Growth Substances / Q000502:physiology*; D006462:Hemolytic Plaque Technique; D007376:Interleukin-2 / Q000502:physiology*; D015847:Interleukin-4; D015848:Interleukin-5; D007519:Isoantigens / Q000276:immunology; D007700:Kinetics; D008212:Lymphocyte Depletion; D008222:Lymphokines / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D012756:Sheep; D013296:Streptococcus pneumoniae / Q000276:immunology; D013601:T-Lymphocytes
D000942:Antigens, Bacterial; D000955:Antigens, T-Independent; D006133:Growth Substances; D007376:Interleukin-2; D015848:Interleukin-5; D007519:Isoantigens; D008222:Lymphokines; D015847:Interleukin-4