Peritoneal Macrophages in the Immune Response to SRBC <em>in vitro</em>.

The role of macrophages in the immune response against SRBC in spleen cell suspension cultures obtained from mice was studied. 1. The presence of macrophages increases the number of PFC against SRBC in spleen cell cultures. 2. The ratio peritoneal exudate cells to spleen cells is very critical. Two × 10⁵ peritoneal exudate cells preincubated with sheep red blood cells stimulate 1 × 10⁷ mouse spleen cells to an optimal response. This reaction is suppressed when 2 × 10⁶ peritoneal cells are used. 3. Spleen cell populations which had lost the capability of producing antibodies by elimination of cells adhering to glass yielded a strong immune response upon addition of 2 × 10⁵ peritoneal exudate cells. The significance of macrophages for the induction of the immune response is discussed. [ABSTRACT FROM AUTHOR]