Altered interleukin production during Friend leukemia virus infection

Spleen cells from BALB/c mice, infected 14 to 28 days earlier with Friend leukemia virus (FLV), were shown to be inhibited in their ability to produce interleukin 2 (IL-2) when stimulated with mitogen. Likewise, these spleen cell populations failed to respond following mitogenic stimulation or exogenous addition of recombinant IL-2. By contrast, the FLV-infected spleen cell populations produced normal levels of interleukin 1 (IL-1) and thymocytes from FLV-infected mice responded normally to addition of exogenous IL-1. This suggests that FLV infection selectively affects the ability of spleen cells to produce cytokines. Spleen cell populations enriched for T lymphocytes and depleted of tumor cells by density gradient centrifugation in Ficoll were unable to produce IL-2. This indicates that the failure to detect IL-2 in cells from FLV-infected mice was not due to a dilution of T lymphocytes by tumor cells but was a functional inability to produce IL-2. Furthermore, enriched T lymphocytes from FLV-infected mice failed to respond blastogenically to exogenous IL-2. Additional studies indicate that tumor cells, but not macrophages or T lymphocytes from FLV-infected spleens, suppressed the blastogenic response to mitogens and IL-2 production by normal splenic T lymphocytes.