Macrophage-lymphocyte interaction in response to a bacterial antigen (E. coli).

The interactions of human lymphocytes with autologous macrophages in response to a clinically relevant particulate bacterial antigen (E coli) have been investigated. Macrophages were required as accessory cells for the E coli induced activation of both T and B lymphocytes. Lymphocyte activation was assayed by determining the degree of proliferation (measured by 3H-thymidine incorporation). The proliferative response was dependent on the number of macrophages and on the amount of antigen in the culture. Macrophages briefly exposed to E. coli acquired the ability to stimulate unfractionated lymphocytes, T and B cells in the absence of free antigen. The in vitro kinetics of this reaction has been determined and analysed with respect to polyclonal B cell response and the antigen specific T cell response.