Regulation of immune responses in SJL and F1 hybrid mice by γ-irradiated syngeneic lymphoma cell

Syngeneic mixed lymphocyte-stimulating la⁺ lymphomas of SJL mice [reticulum cell sarcoma(s) (RCS)] were found to modulate immune responses in vivo. Simultaneous injection of 2×10⁷ γ-irradiated or glutaraldehyde-fixed RCS cells with the antigen sheep red blood cells (SRBC) or 2,4,6-trinitrophenol (TNP)-Ficoll markedly suppressed the subsequent plaque-forming cell response in the spleen. The suppression of the anti-SRBC response was prevented by pretreatment of the mice with cyclophosphamide, whereas the suppression of the anti-TNP-Ficoll response was not affected. RCS injection induced high interferon serum titers within 24 hours after injection, which were not prevented by pretreatment with cyclophosphamide. Injection of γ-irradiated RCS cells (γ-RCS) or RCS cell extract 2 days prior to antigen enhanced the anti-SRBC but markedly suppressed the anti-TNP-Ficoll response. Injection of RCS both on day -2 and day 0 enchanced the anti-SRBC response. SJL mice 8–9 months of age showed much less or no suppression when γ-RCS cells were injected on day 0. Certain F₁ hybrids of SJL also showed the γ-RCS-induced suppression of the anti-SRBC response. Suppression was seen in SJL x BALB.B but not in SJL x BALB/c mice and in SJL x A.TH but not in SJL x A.TL mice, suggesting an/-region effect. F₁, hybrids of SJL by B10 background mice showed no significant suppression. Enhancement of the anti-SRBC response by prior injection of γ-RCS was seen in all F₁ hybrid mice examined.