Isotype, distribution and target analysis of lymphocyte reactive antibodies in patients with human immunodeficiency virus infection

Anti-lymphocyte (ALA) antibodies were investigated by using both microcytotoxicity and immunofluorescence analyses in 87 subjects with different clinical features of human immunodeficiency virus (HIV) infection. A similar mean percentage of killing in microcytotoxicity assays using heterologous lymphocytes as cellular target was recorded in four groups of patients, including 36 HIV-seropositive asymptomatic subjects, 34 patients with HIV-induced lymphadenopathy syndrome (LAS), 13 with acquired immunodeficiency syndrome (AIDS)-related complex (ARC), and 4 patients with the full-blown AIDS. Conversely, an increasing percentage of ALA-positive subjects paralleled the evolution of the HIV infection. The majority of ALA were IgM isotype with a significant reactivity against T cells. This specificity was indifferently directed to CD3 +, CD4 +, and CD8 + lymphocytes. In additional experiments employing enzymatic digestion of lymphocyte membrane antigens, we demonstrated that CD4 and CD8 receptors were digested by the pronase, whereas CD3 molecules were highly resistant. Subsequent flow cytometry analyses using these pronase-digested T cells showed that reactivity of ALA for their target was unchanged. Our data suggest that antigenic specificities of ALA in HIV infection are resistant to pronase treatment and are not related to CD4 and CD8 molecules.