Effects of bovine serum albumin on normal human lymphocytes.

In the course of other experiments we noted increased tritiated thymidine uptake by normal human peripheral blood lymphocytes (PBL) cultured in medium supplemented with bovine serum albumin (BSA) as compared with human plasmas. We confirmed specific stimulatory effects of BSA and sought evidence supporting antigenicity of BSA for human lymphocytes in culture. The PBL cultured in 0.6%-10% BSA incorporated several fold more [3H]thymidine than did cells in medium alone or in human, dog, rat, or guinea pig serum albumins. Responses were maximal for 1% BSA in 7-day cultures. Nonhuman cells (mouse splenocytes) responded comparably in medium and in human, bovine, dog, rat, andf guinea pig albumins. Human lymphocyte donor plasmas contained agglutinators of sheep red blood cells coated with BSA. Agglutination was inhibited by both BSA and antihuman immunoglobulin. These data established specific in vitro stimulatory effects of BSA and suggested that the explanation for this response is that BSA is antigenic to human PBL. Appreciation of such effects is important in conducting and interpreting tissue culture experimentation.