Suppression of human lymphocyte mitogen response by retroviruses of type D. I. Action of highly purified intact and disrupted virus.

The type D retrovirus PMFV, derived from a human cell line, suppresses the in vitro response of human lymphocytes to different T-cell mitogens as well as the mixed lymphocyte reaction. The suppressive effect is virus-specific and the active fraction copurifies with the virus particles. The suppression is produced by both crude and highly purified intact and disrupted virus preparations. However, the suppressive activity of virus disrupted by ether or a detergent is higher as compared with intact virus. The absence of any factors cytotoxic for lymphocytes or lymphoblasts in the suppressive virus preparation is shown by different methods.