The BRB determined the amino acid sequences of about 640 samples. About 440 of these analyses were for unknown protein or peptides and the remainder were for quality control of synthetic peptides. Most of the unknown sequences determined (about 250) were of endogenous peptides eluted from mouse d and b haplotype class I molecules (LI/NIAID, D. Margulies) and from human HLA-A3, -A2, -B27, -B14, -B8 and -A1 molecules (BRB). From these analyses, amino acid residues in peptides requisite for peptide binding to particular class I molecules have been determined. This information has been used to search protein sequence databanks for potential antigenic T cell epitopes that are recognized by cytotoxic T lymphocytes which has important implications for vaccine development. Using such an approach several new antigenic epitopes recognized by cytotoxic T lymphocytes specific for influenza virus proteins have been identified. In addition, proteins from a large variety of sources have been sequenced by the facility. These include Crytococcal enzymes and capsular proteins (Williamson, LCI); a filarial protective antigen (Nutman, LPD); Toxo. gondii antigenically active peptides (Sher, LPD); MHC class I endogenous and antigenic peptides (Margulies, LI); Malaria protein vaccine candidates (Miller and Kaslow, LMR); HIV integrase and uncharacterized HIV proteins (Theodore, LMM) and tumor asscoiated antigens (Seon, Roswell Park Memorial Cancer Institute). We examined the effect on thrombin on astrocytic endothelins and report that endothelin-1 is released into the culture fluid in response to thrombin treatment. Astrocytic production of endothelin-1 appeared to be postranscriptionally regulated. We also found that two endothelin receptor genes (ETA and ETB) were transcribed in primary astrocyte cultures and that ETA mRNA was down regulated in response to thrombin and entothelin-1. These studies indicate a role for thrombin in the regulation of brain perfusion through astrocytic endothelin-1 expression. In an attempt to explore the potential role of endothelins in HIV infection, we investigated the effect of the HIV-1 glycoprotein 120 on monocytic endothelin-1 production. We found that glycoprotein 120, similar to LPS, stimulates the secretion of endothelin-1, as well as TNF- alpha, from macrophages in a concentration-dependent manner. Using reverse transcriptase polymerase chain reaction, we found that circulating monocytes in HIV-infected individuals show a distinct expression of the endothelin-1 gene that is not detectable in healthy controls, indicating chronic activation of this gene in HIV-infection. In addition, cerebral macrophages in patients with HIV encephalopathy were strongly positive for endothelin. Thus, monocytic endothelins appear to be stimulated during HIV infection. Their potent vasoactive properties render them potential candidates for mediating alterations in the cerebral perfusion pattern associated with the AIDS dementia complex.
