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Patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related conditons are known to have abnormalities of T cell subpopulations, including a decreased helper/inducer (bearing the CD4 antigen) to suppressor/cytotoxic (bearing the CDS antigen) T cell ratio and decreased absolute numbers of T cells with the CD4+phenotype1,2. Infection of T cells with a retrovirus, termed human immunodeficiency virus (HIV), is thought to be important in these abnormalities3–5. HIV infection alone does not adequately explain the CD4+T-cell abnormalities seen in AIDS, however, and the nature of T-cell destruction in this disease remains poorly characterized6. Here we describe an AIDS-related serum autoantibody that reacts with an antigen of relative molecular mass 18,000 (M r18K) restricted to lectin-stimulated or HIV-infected CD4+T cells. The antibody also suppresses proliferation of CD4+T cells in vitro and induces cytotoxicity of these cells in the presence of complement. Its role in the development of AIDS merits attention.

Scrapie is a slow infection of the nervous system which progresses in the absence of any apparent immune response1–8. The recent development of a large-scale purification protocol for scrapie prion9made it possible to obtain substantial quantities of electrophoretically purified prion protein (PrP 27–30) and we report here on the successful production of a rabbit antiserum to PrP 27–30. The antiserum reacted with PrP 27–30 and several lower molecular weight proteins as shown by Western blots; it did not react with protein preparations from uninfected brains. Discrete structures in the subependymal region of scrapie-infected hamster brains were stained immunocytochemically. These same structures also stained with Congo red dye and showed green birefringence with polarized light, a characteristic of purified prion rods9. This staining pattern suggests that they are amyloid plaques.