title: Distinct patterns of Bcl-2 expression occur in R5- and X4-tropic HIV-1-producing lymphoid tissue cells infected ex vivo.
abstract: Most HIV-1 replication occurs in secondary lymphoid tissues in T cells within B cell follicles. Mechanisms underlying the accumulation of HIV-1-producing cells at these sites are not understood. Antiapoptotic proteins such as Bcl-2 could promote follicular CD4(+) T cell survival, contributing to sustained virus production. Tonsils obtained from subjects without known HIV infection were disaggregated and analyzed for Bcl-2 expression in follicular (CXCR5(+)) and extrafollicular (CXCR5(-)) CD3(+)CD4(+) cells by flow cytometry. Additional tonsil cells were cultured with phytohemagglutinin (PHA) and interleukin-2 (IL-2) for 2 days, infected with either CCR5(R5) or CXCR4-tropic (X4) GFP reporter viruses, and analyzed for Bcl-2 expression. In freshly disaggregated CD3(+)CD4(+) tonsil cells, mean florescence intensity (MFI) for Bcl-2 was higher in CXCR5(+) (median, 292) compared to CXCR5(-) cells (median, 194; p=0.001). Following in vitro stimulation with PHA and IL-2, Bcl-2 MFI was higher in both CXCR5(+) cells (median, 757; p=0.03) and CXCR5(-) cells (median, 884; p=0.002) in uninfected cultures compared to freshly isolated tonsil cells. Bcl-2 MFI was higher in GFP(+)CD3(+)CD8(-) R5-producing cells (median, 554) than in X4-producing cells (median, 393; p=0.02). Bcl-2 MFI was higher in R5-producing CXCR5(+) cells (median, 840) compared to all other subsets including R5-producing CXCR5(-) cells (median, 524; p=0.04), X4-producing CXCR5(+) cells (median, 401; p=0.02), and X4-producing CXCR5(-) cells (median, 332; p=0.008). Bcl-2 expression is elevated in R5 HIV-1-producing CXCR5(+) T cells in vitro, which may contribute to propagation of R5 virus in B cell follicles in vivo.
authors.affiliation: 1 Division of Infectious Diseases, Department of Medicine, University of Colorado , Denver, Aurora, Colorado.
authors.forename: Michelle K
authors.initials: MK
authors.lastname: Haas
authors.forename: David N
authors.initials: DN
authors.lastname: Levy
authors.forename: Joy M
authors.initials: JM
authors.lastname: Folkvord
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Connick
mesh_terms: D000293:Adolescent; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D020869:Gene Expression Profiling; D015497:HIV-1 / Q000254:growth & development*; D006801:Humans; D016130:Immunophenotyping; D008221:Lymphoid Tissue / Q000473:pathology*; D008297:Male; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D019718:Receptors, CXCR4 / Q000032:analysis*; D054380:Receptors, CXCR5 / Q000032:analysis*; D015728:Receptors, HIV / Q000032:analysis
chemical_list: C527276:CXCR4 protein, human; C095085:CXCR5 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D019718:Receptors, CXCR4; D054380:Receptors, CXCR5; D015728:Receptors, HIV