Evidence of interleukin-1-like activity associated with bovine serum albumin.

Little information is available concerning the "spontaneous" Interleukin-1 (IL-1) which occurs in vivo without apparent stimulation. Although PHA and con A-suboptimally induced, and PPD-induced, lymphocyte responses in 0.25% BSA containing serum-free medium were markedly depressed when Mø was depleted, there was no significant reduction of the response of Mø-depleted lymphocytes in 2% BSA. In addition, lymphocyte transformation in 2% BSA exhibited enhancement of response of Mø-depleted lymphocytes when compared to the response of Mø-depleted lymphocytes in 0.25% BSA. These observations indicate that an IL-1-like activity is not only found in normal bovine serum but also may have an in vivo function modulating lymphocyte response to antigen.