SINGLE CELLS RESPONDING TO TWO UNRELATED ANTIGENS

Publisher Summary This chapter highlights how single cells respond to two unrelated antigens. The immunization of mice with two unrelated antigens can result in regular appearance of spleen cells simultaneously reacting to both antigens, provided that the two antigens induce a rapid and vigorous cell response. This can be achieved by using erythrocytes for eliciting primary response or hapten-carrier conjugates for challenging animals previously primed with the same conjugates given in mixture with complete Freund's adjuvant. The use of hapten-carrier conjugates as immunogens enabled a satisfactory characterization of the specificity of the cellular response. The absence of cross-reactions between the haptens of the pairs used was further ascertained by specific inhibition experiments at the single-cell level. Almost all double PFC that remained active in the three successive media, lysed only one indicator (erythrocyte) when transferred into the second medium containing the alternate soluble inhibitor and again lysed both indicators after transfer into the third inhibitor free medium. When double PFC were individually cultured, they yielded a progeny of daughter PFC lysing only one or the other indicator red cells. Thus of the double lytic activity of parental PFC, only one was inherited in the daughter PFC after division. Another feature of the progeny of single cells from animals immunized with two antigens was discovered by use of individual cell culture method. High frequency of antigen-binding cells for a variety of antigens and of cells bearing specific receptors for two antigens suggest that more than one pair of V genes can be expressed on the same cell.