H-2 antigen expression: Loss in vitro, restoration in vivo, and correlation with cell-mediated cytotoxicity in a mouse lymphoma cell line.

The susceptibility to cell-mediated cytolysis of cells of the recently developed C57BL/Ka(H-2 ( b )) lymphoma cell line, BL/VL(3), was investigated in allogeneic assays with thymus-dependent lymphocytes (T cells). Compared to EL4, the widely used C57BL/6(H-2 ( b )) lymphoma cell line, BL/VL(3) cells were found to be insensitive to T-cell-mediated lysis as detected by the use of(51)Crrelease methods. When used as immunogens in alloreactive combinations with BALB/c(H-2 ( d )) splenocytes as responder cells, BL/VL(3) cells failed to elicit sensitization. Serological tests showed that this cell line had profoundly reduced levels of H-2(b) antigens on its surface. When BL/VL(3) cells were reinjected into C57BL/Ka and BALB/c mice, full recovery of H-2(b) antigen expression at the cell surface was observed in both syngeneic and allogeneic hosts after only 11 days of in vivo growth. Concomitantly, they acquired the ability to induce cytotoxic responses in allogeneic T cells and became susceptible to their lytic activity. The expression of H-2 antigens on the surface of BL/VL(3) cells is a reversibly modulated function that depends on in vivo growth conditions and is lost in vitro in the absence of immunoselective pressure.