INDUCTION OF AN ANTIBODY-RESPONSE IN CULTURES OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES

A culture system is described which provides adequate conditions for in vitro immunization of human peripheral blood lymphocytes to heterologous erythrocytes. Making use of this method, with a number of different donors, an antibody response was obtained which peaked at about day 8 of culture with 30-300 plaque-forming cells (PFC) per 106 input lymphocytes. In a number of experiments, poor or negative results were obtained, even with donors that previously gave a good response. This variability in the results was not due to a too low number of precursor cells present in the blood and could be overcome by treating the cells, before initiation of the culture, with a factor produced by mouse T [thymus-derived] cells educated to sheep erythrocytes (SRBC). Under these conditions, a PFC response was obtained which peaked at about day 8 and which in some experiments could be as high as 20,000 PFC per 106 input lymphocytes. Paralleling the increase in PFC was an increase in cell number. The cells recovered from the treated cultures were at all times more numerous than in the non-treated cultures. The height of the proliferative and antibody-producing responses varied from experiment to experiment, with a higher proliferative response accompanying a higher PFC response. Although the mechanisms of the in vitro antibody response need to be clarified, this system may become a useful tool in studying the immune response in man.