Human serum albumin as a substitute for foetal calf serum in blast transformation assays and cytogenetic analyses.

: Diverse factors in serum produce complex effects on lymphocytes. Indeed, when used as a protein supplement for lymphocyte culture, serum has many disadvantages. A need exists for media in which serum is replaced by purified active serum components. The in vitro effects of human serum albumin (HSA) were evaluated and compared with the widely used foetal calf serum (FCS). Unstimulated and mitogen-activated lymphocyte proliferation was measured by 3H-thymidine incorporation. Phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were used to transform the lymphocytes obtained from 36 healthy adults. Six concentrations of HSA, 0.5, 1, 2.5, 5, 10 and 20%, were studied. The last two concentrations produced an inhibition of lymphocyte proliferation. HSA, which was not itself mitogenic permitted a 4- to 5-fold higher transformation than 10% FCS. Maximum transformation occurred at HSA concentrations between 2.5 and 5% for PHA and PWM, and between 1 and 2.5% for Con A. In whole-blood lymphocyte cultures, the addition of 1% HSA gave a number of mitoses comparable to that obtained with the 10% FCS supplement. HSA is an interesting substitute for FCS: it is chemically well understood and standardized, species specific, readily available, relatively inexpensive, and has a long shelf life. HSA appears to be an excellent protein supplement for support of human lymphocyte proliferation in vitro, and can be recommended for routine use in lymphocyte cultures.