Effect of inhibitors of macromolecular synthesis on HL-A antibody mediated lysis of cultured lymphoblasts.

The effect of inhibitors of macromolecular synthesis on the cell surface expression of HL-A antigens of cultured lymphoblastoid cells has been investigated by utilizing the complement dependent cytotoxic reaction and the absorption test. Cultured human lymphoid cells (WI-L2 and RPMI 8866) treated with actinomycin D do not show any change in the expression of HL-A antigens, while RAJI cells incubated with the same drug display a reduced absorbing capacity for HL-A alloantisera. Cycloheximide does not affect the absorbing capacity of lymphoblastoid cells, but tends to increase their reactivity in the cytotoxic test with HL-A alloantisera and complement. Puromycin, which like cycloheximide inhibits protein synthesis but by a different mechanism, decreases the cell surface expression of HL-A antigens. The effect of puromycin is not due to steric hindrance since analogues of puromycin which do not inhibit protein synthesis do not change the absorbing capacity of lymphoblastoid cells for HL-A alloantisera. The limitations of the complement dependent cytotoxic test in quantitating antigens on cell membranes are discussed. It is proposed that HL-A antigens which have been extensively characterized as to their genetical, serological, and chemical properties can be utilized as markers to characterize cell membrane metabolism.