DEMONSTRATION OF HEAVY AND LIGHT CHAIN ANTIGENIC DETERMINANTS ON THE CELL-BOUND RECEPTOR FOR ANTIGEN : SIMILARITIES BETWEEN MEMBRANE-ATTACHED AND HUMORAL ANTIBODIES PRODUCED BY THE SAME CELL

High-rate antibody-forming cells and immunological memory cells can be selectively retained if filtered through a column coated with relevant antigen. This trapping can be blocked if the cells are incubated with an anti-immunoglobulin serum prior to column passage. A similar blocking is not observed when cells are treated with an anti-lymphocyte serum, thereby excluding the possibility that any antibodies combining with surface structures could cause this effect. By the use of antisera specific for heavy or light chain antigens, it was possible to locate such antigens in the antigen-binding receptor areas of immune cells. Criss-cross studies using antisera specific for gamma 1 or gamma 2a heavy chains showed that the membrane receptor has the same heavy chain as will be present in the eventual product of that cell, the humoral antibody.