Altered erythrocyte C3b receptor expression, immune complexes, and complement activation in homosexual men in varying risk groups for acquired immune deficiency syndrome.
We studied levels of erythrocyte C3b receptors (E-CR1) and correlated them to the level of circulating immune complexes (CIC) and complement activation in patients with or at risk for acquired immunodeficiency syndrome (AIDS). A significant reduction was found in patients with AIDS (185 +/- 93 CR1/cell), AIDS-related complex, and generalized lymphadenopathy, whereas healthy male homosexuals or normal controls had 434 +/- 193 and 509 +/- 140 CR1/cell, respectively (P less than 0.001). Family studies indicate that this defect is acquired. Reduction in E-CR1 was associated with increased levels of CIC when assayed by binding to Raji cells, but not when tested by C1q binding. Complement activation was assessed by levels of C3bi/C3d-g in plasma, measured with a monoclonal antibody specific for a neoantigen in C3d. AIDS patients had increased C3 activation (2.68 +/- 1.67%) when compared with normal controls (0.9 +/- 0.22%) (P less than 0.01). The decreased E-CR1, the presence of CIC, and C3 activation suggest that complement activation by immune complexes may play a role in the clinical expression of the disease.
D000386:AIDS-Related Complex / Q000276:immunology; D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology*; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral / Q000032:analysis; D000936:Antigen-Antibody Complex / Q000032:analysis*; D001323:Autoantibodies / Q000032:analysis; D003166:Complement Activating Enzymes / Q000378:metabolism; D003167:Complement Activation; D015922:Complement C1q; D004912:Erythrocytes / Q000378:metabolism*; D015483:HIV Antibodies; D006716:Homosexuality; D006801:Humans; D008206:Lymphatic Diseases / Q000276:immunology; D008297:Male; D011951:Receptors, Complement / Q000096:biosynthesis*; D017463:Receptors, Complement 3b; D012306:Risk
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D015483:HIV Antibodies; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D015922:Complement C1q; D003166:Complement Activating Enzymes