Analysis of serum samples from patients with the acquired immunodeficiency syndrome (AIDS) was performed by high-resolution zone electrophoresis. A high incidence of monoclonal and oligoclonal immunoglobulins was detected in the sera of 24/27 patients with Kaposi's sarcoma and in 2/15 patients with opportunistic infections. The presence of monoclonal bands was independent of whether or not the patients had experienced an opportunistic infection. These findings indicate a monoclonal or oligoclonal B-cell activation occurring in a much higher frequency in AIDS patients with Kaposi's sarcoma, thus suggesting that similar mechanisms may be operative in the malignant or pseudomalignant proliferation of B-cells and endothelial cells in patients with AIDS.

Acquired Immunodeficiency Syndrome/*IMMUNOLOGY Antibodies, Monoclonal/*IMMUNOLOGY B-Lymphocytes/IMMUNOLOGY Bacterial Infections/IMMUNOLOGY Human IgA/ANALYSIS IgG/ANALYSIS Immunoglobulins/*ANALYSIS Male Sarcoma, Kaposi's/IMMUNOLOGY JOURNAL ARTICLE

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