Natural and Antibody-Induced Adherence of Guinea Pig Phagocytic Cells to Autologous and Heterologous Thymocytes

Abstract

Adherence of macrophages and thymocytes occurs in cell mixtures containing untreated guinea pig macrophages and autologous or homologous thymocytes. Morphologically the reaction resembles the adherence of guinea pig macrophages to heterologous lymphocytes which has been induced by moderate concentrations of antilymphocyte serum. There is relatively little natural adherence of guinea pig macrophages to rat, mouse, and rabbit thymocytes or to extra-thymic guinea pig lymphocytes. Adherence of autologous or homologous guinea pig macrophages and thymocytes occurs in the absence of serum but is augmented when guinea pig serum or gelatin is present. At high serum concentrations the adherence is often followed by phagocytosis of autologous thymocytes by the macrophages. When serum is incubated at 57°C for 30 min its ability to induce phagocytosis is abolished but its ability to enhance adherence is not. Dialysis of serum against salt solution does not affect its ability to enhance adherence or phagocytosis. Treatment of macrophages with trypsin completely abolishes the adherence of autologous macrophages and thymocytes. The degree of adherence of guinea pig neutrophils and eosinophils to autologous and homologous thymocytes exceeds their adherence to extra-thymic guinea pig lymphocytes or heterologous thymocytes but is less than the adherence of guinea pig macrophages. Comparative studies have indicated that the adherence of autologous macrophages and thymocytes does not occur through any of the known opsonic actions of circulating antibodies. It is postulated that adherence of autologous macrophages and thymocytes may participate in mechanisms which limit the number and circulation of thymocytes.