Immunoglobulin determinants on the surface of human lymphocytes

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.

Separation of normal and immune lymphoid cells by antigen-coated coated columns. Antigen-binding characteristics of membrane antibodies as analyzed by hapten-protein antigens

Specific fractionation of immunologically competent cells derived from normal or immune animals was achieved by filtration through antigen-coated bead columns. This selective retention of the relevant reactive cells could be shown to produce a cell population, which after passage through the column would behave like a suspension rendered immunologically tolerant by "classical" means. The immunologically specific elimination of potential antibody-forming capacity of the filtered cells could be shown to affect the IgM and the IgG system to a similar extent. Analysis of the binding characteristics of the membrane antibodies responsible for this selective retention indicate striking similarities to those of the humoral antibodies produced against the antigen. Thus, the surface receptor could distinguish isolated haptenic groups on a "foreign" carrier background and the receptor of the hapten-reactive cells in the present system (high-rate antibody-forming cells against NIP) failed to combine with carrier specific determinants in analogy with the binding behavior of the serum anti-hapten antibodies. The binding of anti-hapten reactive cells to bead-attached haptens could be specifically inhibited by the presence of free hapten in the columnar fluid during cellular filtration. The results strongly suggest that the potential humoral antibody-forming cell has preformed receptors on its outer surface with binding characteristics, indicating similarity, if not identity, to those of the eventual product of the cell, the humoral antibody.