MACROPHAGE REQUIREMENT FOR THE INVITRO RESPONSE TO AN INSOLUBILIZED T-INDEPENDENT ANTIGEN

The role of macrophages in the in vitro response of mouse spleen cells to the insolubilized, T‐independent antigen trinitrophenylated polyacrylamide (TNP‐PAA) is demonstrated by the following points. The response is abolished by filtration on Sephadex G‐10 and can be restored by the addition of splenic adherent cells, deficient in either B or T cells, or by 2‐mercaptoethanol (2‐ME). It is suppressed upon elimination of phagocytic cells by silica, and restored by 2‐ME. 2‐ME can restore a normal response from zero, in cultures depleted of both adherent and phagocytic cells, and is efficient in the absence of mature T cells. Experiments in microcultures show that large numbers of macrophages can stimulate a supra‐optimal response from B cells. This response is only obtained in the presence of the antigen, and is specific for TNP. These results show that macrophages, probably by their polyclonal B‐cell activator (PBA) property, play a role in the specific response to TNP‐PAA. This prompts us to discuss the respective roles in the B‐cell response of this PBA activity and of the interaction of the antigen with the specific B‐cell receptors. Copyright © 1979, Wiley Blackwell. All rights reserved