Immunologic tolerance to antigens associated with murine leukemia viruses: T-cell unresponsiveness?

Abstract

To test whether the cell-mediated immune response of murine leukemia virus (MuLV) carrier mice is specifically depressed, adult C57BL/6 mice, neonatally infected with Moloney (M)-MuLV, were immunized with M-MuLV-induced leukemia BALB/c cells (YC8, LSTRA). Their spleen lymphocytes were assayed at various intervals after immunization with syngeneic M-MuLV-induced leukemia cells (MBL-2) by use of 51Cr-releasing lymphocyte-mediated cytotoxicity (LMC). In contrast with similarly immunized control mice, spleen lymphocytes from M-MuLV neonatally infected mice showed no reactivity, but these cells were fully reactive when tested against radiation-induced leukemia BALB/c cells (BALB.RL♂1). No blocking activity to M-MuLV-associated antigens was found with different sera from M-MuLV neonatally infected and immunized mice. These results, together with the finding that the active lymphocytes in LMC were sensitive to pretreatment with anti-θ serum, suggest that a state of thymus-derived (T)-cell unresponsiveness occurs in neonatally infected mice. Though the neutralizing antibody to M-MuLV was not found in M-MuLV neonatally infected C57BL/6 mice, we demonstrated in another study the presence of specific humoral antibody to M-MuLV reverse transcriptase in the kidney eluate of similarly treated C57BL/6 mice. Therefore, partial tolerance to M-MuLV-associated antigens occurred in this system.