Isolation of cytomegalovirus-specific cytotoxic T-lymphocytes from gut-associated lymphoid tissue (GALT) of HIV type 1-infected subjects

Cytomegalovirus (CMV) can be an important opportunistic infection in HIV-1- infected patients, particularly when the CD4(+) T-cell count drops below 50 lymphocytes/mm(3), CMV-associated disease, including retinitis, pneumoniti s, gastroenteritis, and encephalitis, is estimated to affect up to 40% of A IDS patients. We have studied the cellular immune response to CMV in gut-as sociated lymphoid tissue (GALT) of HIV-1-infected patients, Two patients wi th chronic diarrhea of unknown etiology were examined by flexible sigmoidos copy and upper endoscopy, Biopsy specimens were obtained from lymphoid-asso ciated tissue sites in rectum and duodenum. Both patients were seropositive for CMV IgG, but had not been treated with ganciclovir, and neither had cl inical signs of CMV disease. Mononuclear cell cultures were established fro m GALT and blood and assayed for the presence of CMV-specific CD8(+) T cell s. CD8(+) T-cell phenotype and function were assessed by MHC Class I tetram er staining, using an HLA-A*0201 tetramer complex specific for peptide 495- 503 (NLVPMVATV) of CMV lower matrix protein pp65, and by a standard Cr-51 r elease assay. CMV pp65-specific cytotoxic lymphocytes (CTL) were detected i n GALT and blood MNC from both patients, These results demonstrate that HIV -1-infected subjects seropositive for CMV, but without active CMV gastroint estinal disease, harbor CMV-specific CTL in intestinal lymphoid tissue. Thi s is the first report of isolation of CMV-specific CTL in GALT and will lea d to greater understanding of the pathogenesis of CMV disease in human muco sal tissue.