Autoimmune anti-HIV-1gp120 antibody with antiidiotype-like activity in sera and immune complexes of HIV-1-related immunologic thrombocytopenia.
Autoimmune antiidiotype-like antibody (Ab2) directed against anti-HIV-1gp120 (Ab1) was found in high titer in the sera of 10 consecutive homosexual and 11 narcotic addict HIV-1-related immunologic thrombocytopenia (HIV-1-ITP) patients, was barely detectable in 10 nonthrombocytopenic HIV-1 sero-positive individuals, and was not detectable in 5 normal subjects by use of a solid-phase RIA. Reactivity of autologous Ab2 for Ab1 was 4-120-fold greater than Ab2 for homologous Ab1. Affinity-purified Ab2 did not block the binding of affinity-purified Ab1 to its HIV-1gp120 epitopes on immunoblot, indicating the absence of "internal image" antiidiotype. Both Ab1 and Ab2 are precipitable from sera with polyethylene glycol (PEG) and present in a macromolecular complex that is excluded by gel filtration on G200 and contains IgG, IgM, C3, and the anti-F(ab')2 antiidiotype-like complex. PEG-precipitable complexes bind to platelets in a saturation-dependent manner. Neither affinity-purified Ab1 nor Ab2 binds to platelets. However, the combination of Ab1 and Ab2 (preincubated for 2 h at 22 degrees C) binds to platelets in a saturation-dependent manner at an optimum ratio range of 10-20:1. Ab2 reactivity correlates with serum PEG-precipitable immune complex level (r = 0.91; P less than 0.001) and with thrombocytopenia (r = 0.89; P less than 0.001). We suggest that the anti-HIV-1gp120 antiidiotype-like complex contributes to the markedly elevated platelet Ig and C3 level of HIV-1-ITP patients and propose that this may contribute to their thrombocytopenia.
Karpatkin
S
S
New York University Medical School, Department of Medicine, New York 10016.
Nardi
M
M
D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology*; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis*; D000936:Antigen-Antibody Complex / Q000032:analysis*; D001323:Autoantibodies / Q000032:analysis*; D001792:Blood Platelets / Q000276:immunology; D002850:Chromatography, Gel; D015699:HIV Envelope Protein gp120 / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D013921:Thrombocytopenia / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D015699:HIV Envelope Protein gp120; D007074:Immunoglobulin G; D007075:Immunoglobulin M