Immune receptors (IgG-Fc and complement receptors) in normal human organs

The presence of immune receptors (IgG-Fc and complement receptors) was examined in normal human tissues from various organs. Sheep erythrocytes sensitized with rabbit IgG antibody (IgG-EA) or with rabbit IgM antibody and human complement (IgM-EAC) were used for the detection of IgG-Fc receptors and complement receptors, respectively. IgG-Fc receptors were detected on sinuses of the lymph node, splenic red pulps, hepatic lobules, renal glomeruli, alveolar wall of the lung, intestinal villi, superifical layer of the synovium, and subcutaneous tissue. The presence of complement receptors was demonstrated in the follicles and the sinuses of lymph nodes, white pulp of the spleen, renal glomeruli, alveolar wall of the lung, and lamina propria of the intestine. The specific binding of IgG-EA was consistently inhibited by heat-aggregated human IgG or by a high concentration of native human IgG. The detection of immune receptors in these various tissues might be helpful for understanding why the immune complexes are often detected when immunologically mediated disease processes involve these tissues.