Malignant lymphomas in the acquired immunodeficiency syndrome. Additional evidence for a B-cell origin.

An increased incidence of high-grade malignant non-Hodgkin's lymphomas has been reported in homosexual men. This phenomenon appears to represent another facet of the acquired immunodeficiency syndrome (AIDS). Histologically, the majority of these lymphomas have been small noncleaved cell lymphomas or immunoblastic lymphomas, subtypes most commonly associated with a B-cell phenotype, but immunologic data supporting this have been limited. Using a plastic embedding technique, we have examined a series of 31 malignant lymphomas, including nine from the central nervous system (CNS), in patients with AIDS or at high risk for AIDS. All 31 of the lymphomas were positive with one or more of the following B-cell markers: HLA-DR/la, Pan B, Leu 12, Leu 14, and IgM. All 31 were negative for the pan-T reagent Leu 4 and myeloid-macrophage markers (Leu M1, nonspecific esterase). In addition, seven of the nine CNS lymphomas showed strong plasma membrane staining for adenosine triphosphatase, a B-associated marker. These findings provide strong immunologic evidence for a B-cell origin in the lymphomas of AIDS.