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Phenotypic and Lymphokine Profile of the Effector Cells Associated with CD8+ Anti-HIV-1 Suppressor Activity (CASA) J. WILKINSON*1, J. ZAUNDERS1, N. NEWCOMBE1, and D. A. COOPER1‚2. 1Ctr. for Immunology, Sydney, Australia and 2St. Vincent's Hosp. and Natl. Ctr. for HIV Epidemiology and Clin. Res., Sydney, Australia A panel of 22 cloned CD8+ T-lymphocyte cell lines from a single patient source and with a broad range in CASA, were generated to assess (a)the identity of the subset responsible for CASA, using 4-colour flow cytometry (b)the lymphokines important for this activity, using intracellular flow cytometry and mRNA expression and (c)the type of anti-HIV activity displayed by the clones. Strong CASA significantly correlated to CD8+ T-cell clones that displayed a high co-expression of the molecule CD28+ (r=0.52, P=0.01) and Ki67+ (r=0.88, P=0.02); with strong CASA clones demonstrating a significantly higher (P<0.05) expression of CD8+CD28+ and CD8+Ki67+ compared to those with weak activity. Enrichment of the CD8+CD28+ population with immunomagnetic beads resulted in a 2-fold increase in CASA, whilst depletion of this subset halved CASA. No such correlations or findings were observed for the markers CD57+, perforin or CD38+HLADR+. Six cloned CD8+ T-cell lines (3 strong and 3 weak CASA clones) were examined for intracellular IL-2, 4, 6, 10, IFN-g, and TNF-a expression using flow cytometry. Strong CASA significantly correlated with an increased level of IL-2 (P=0.05) and a higher expresssion of IFN-g and TNF-a; the Th1 cytokines were generally expressed at higher levels than the Th2 cytokines. RANTES, IP-10 and I-309 mRNA expression were significantly (P<0.05) elevated in CD8+ clones exhibiting strong CASA compared to those with weak, whereas the expression of IFN-g and IL-13 were significantly greater in the weaker CASA cohort compared to the strong. There was no significant differences between these 2 cohorts in the expression of the lymphokines IL-2, 4, 5, 8, 9, 10, 14, 15, MIP-1a, MIP-1b, MCP-1 and Ltn. Seven clones, exhibiting a broad range of CASA, demonstrated no cytotoxic T-lymphocyte activity to the targets gag, pol, env, nef, gag-pol, RT, tat, gp120 and env MN. The maintenance of CD8+CD28+Ki67+ effector cells and the Th1 cytokine profile are important for strong CASA. Additionally, the secretion of ligands that compete for the HIV co-receptors CCR5 and CCR8 will result in the suppression of replication of M-, T- and dual tropic strains of HIV. Key Words: CD8+ Effector cells, HIV Suppression, HIV-1 disease |
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© 7th
Conference on Retroviruses and Opportunistic Infections, |