Effect of Polyspecific Rabbit Anti-Immunoglobulin Antisera on the Response of Human Lymphocytes in Mixed Lymphocyte Culture

Abstract

The effect of pretreatment of human peripheral lymphocytes with rabbit anti-F(ab′)2 on reactivity in mixed lymphocyte cultures (MLC) was studied in 19 experiments using a one-way system and in 10 experiments with two-way stimulation. In some ‘two-way cultures’, an additive effect of allogeneic lymphocytes and undiluted anti-F(ab′)2 was observed. In the one-way system and in the majority of the two-way MLC tests a marked potentiating effect of the two stimulants could be seen, the activity in most cases being much higher than the sum of the single effects. With neither system could inhibition be observed. In the one-way MLC system, the effect of diluting the antiserum was studied to see if any inhibitory effect could be discovered. At the highest dilution studied (1:10,000), however, there was still no inhibition. It is concluded that the present study does not give evidence of immunoglobulin receptors necessary for the MLC response. The possibility that the lymphocytes stimulated by anti-F(ab′)2 may be different from the cells engaged in the MLC response, is discussed.