Antigen Presentation by Specifically Sensitized Macrophages in Interferon-γ Induction

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Abstract
Antigenic stimulation of specifically sensitized T lymphocytes to interferon-γ (IFN-γ) production requires the presence of macrophages. This study examines the ability of peritoneal macrophages from immunized mice to present the antigen to antigen-specific lymphocytes. Such cells presented purified protein derivative (PPD) of tuberculin at concentrations as low as 0.1 μ/ml to sensitized T lymphocytes. In contrast, peritoneal macrophages from unimmunized animals required 1,000-fold higher concentrations of antigen to stimulate the same lymphocytes. The presentation of low concentrations of antigen by macrophage from immunized animals was significantly blocked by anti-immunoglobulin antibody, indicating that the surface immunoglobulin receptors were critically involved in this phenomenon. These results suggest that surface immunoglobulins serve to focus antigens onto specific macrophages and that such cells are highly efficient at presenting linked antigenic determinants to T cells. The implication of these findings for the mechanism of IFN-γ induction are discussed.