| |
Th1/Th2 Cells Influence the Coreceptor Tropism of HIV-1 Isolates O. EQUILS*1, E. GARRATTY2, J. DEVILLE2, K. NIELSEN2, P. KROGSTAD2, and Y. BRYSON2.
1Cedars-Sinai Med. Ctr.; 2Univ. of California at Los Angeles Background: We previously observed a change in the coreceptor tropism(X4 to R5) in the HIV infected children on HAART associated with an increase in naive T cell count. The predominance of Th1/Th2 cells may influence the coreceptor tropism, we therefore determined the role of in vitro differentiated Th1/Th2 cells in coreceptor tropism of HIV isolates pre- and post HAART.
Methods: The magnetic bead selected, anti CD3Ab activated cord and adult CD45+CD4+ cells were induced into Th1 and Th2 by incubating for 10 days in media with IL-2 and either IL-12 or IL-4. Intracellular cytokine production was determined by flow cytometry after PMA and ionomycin stimulation in the presence of brefeldin. Th1/Th2 cells from single donor were infected with 8 primary HIV-1 isolates with known coreceptor tropism (determined in HOS cells expressing CXCR4 or CCR5). HIV replication was measured by the peak p24Ag production in supernate.
Results: 7% of resting Th1 cells produced IL-4 and 12% IFN-gamma, and 4% of resting Th2 cells produced IL-4 and 0.4% IFN-gamma. After activation, 0.6% of Th1 and 7% of Th2 cells were positive for IL-4, and, 69% of Th1 and 4% of Th2 cells for IFN-gamma. Dual tropic (X4+R5) SI isolates (n=4) predominantly infected Th2 cells (mean p24Ag was 32 versus 8,196 pg/ml in Th1 and Th2 cells respectively). R5 tropic NSI isolates (n=4) preferentially infected Th1 cells (mean p24 Ag was 21,720 versus 7,483 pg/ml in Th1 and Th2 cells respectively). The isolates obtained from Th1 cell culture supernates were R5 tropic on HOS cells, despite the fact that 2 were originally dual tropic. The isolates obtained from Th2 cell culture supernates had the same tropism as the original virus (dual/dual, R5/R5).
Conclusion: Although there is no clear separation between Th1 and Th2 cells in humans, naive CD4+ T cells can be induced to predominantly produce either type 1 (IFN-gamma) or type 2 (IL-4) cytokines. In our study, R5 tropic HIV-1 isolates preferentially infected the Th1 cells and dual tropic isolates predominantly infected the Th2 cells. This suggest a potential role for the predominant Th1/Th2 cell type to influence the HIV-1 coreceptor tropism (R5 versus X4 tropic).
Key Words: coreceptor tropism, HAART, Th1 and Th2 cells
|
