The peritoneal antigen‐presenting macrophage: control and immunogenic properties of distinct subpopulations

The control of the immunogenic antigen‐presenting capacity of different subpopulations of thioglycollate‐induced peritoneal macrophages has been investigated. The experiments revealed the existence of two major subpopulations of macrophages, only one of which was highly efficient in educating antigen‐specific T cells. The other subpopulation, while highly phagocytic, was devoid of antigen‐presenting capacity. Further analysis, using specific antisera directed at H‐2I region gene products, revealed that the immunogenic antigen‐presenting population expressed H‐2I region‐controlled membrane antigens. Searching for cellular elements which control the differentiation of this antigen‐presenting macrophage subpopulation, it was found that its function was strictly controlled by T cells. T cell‐deficient mice (nu/nu) failed to generate a functional antigen‐presenting macrophage subpopulation. Transplantation of mature T lymphocytes to T cell‐deprived mice restored the immunogenic function of their antigen‐presenting macrophages. The results obtained suggest the existence of heterogeneity of functions among macrophage subpopulations and add a new regulatory function for T cells.