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Session 42 Poster Presentations
CD8 T-Cell Responses to HIV/SIV
Session Day and Time: Tuesday 1:30 - 3:30 pm
Room: Hall D


318
The Differential Ability of Long-term Nonprogressors and Progressors to Restrict HIV Replication is Not Caused by Loss of Recognition of Autologous Viral Sequences
S. A. Migueles*1, A. C. Laborico1, H. Imamichi2, W. L. Shupert1, C. Royce1, M. McLaughlin1, L. Ehler1, S. Liu1, J. Metcalf1, M. Connors1
1Lab of Immunoregulation, NIAID, NIH, Bethesda, MD and 2Sci Applications Intl Corp Frederick, NCI, MD

Background: Whether the impaired restriction of HIV replication observed in most patients (pts) is caused by the loss of CD8+ T-cell recognition of autologous viral sequences remains unknown. Since the production of antigens that are representative of very diverse in vivo variants is not feasible, the frequency of CD8+ T-cells specific for autologous HIV has not been measured.

Methods: Purified primary CD4+ T-cells were stimulated with anti-CD3/anti-CD28 and cultured in IL-2 containing medium for 9 days to induce replication of autologous virus. High frequencies of CD4+ T-cells expressing HIV p24 (10%–40%) were confirmed prior to use in 6h stimulation assays. CD8+ T-cell responses were measured by intracellular cytokine staining and flow cytometry according to standard protocols. Autologous viral variants were sequenced by limiting dilution RT-PCR of plasma virion RNA. Synthetic peptides corresponding to predicted autologous amino acid sequences were used to confirm responses to autologous virus.       

Results: In 9 B*5701+ pts, 1%–13% of peripheral CD8+ T-cells up-regulated CD69 and expressed IFN-g in response to autologous CD4+ T-cells expressing autologous viral gene products. There were no differences in the responses between 3 long-term nonprogressors (LTNPs) and 6 progressors (means 7.9 ±2.9% vs 8 ±1.9%, respectively; p > 0.5). Except for an E312D mutation in the QASQEVKNW gag epitope (308–316), sequence mutations were not over-represented within B57-restricted gag epitopes in 17 progressors compared with 10 LTNPs. Responses to the E312D variant were more variable in 9 progressors (compared with 5 LTNPs), but this mutation did not reliably confer loss of recognition.

Conclusions: These findings confirm that high frequencies of CD8+ T-cells recognizing autologous virus sequences are present in the peripheral blood of patients with poor immunologic restriction of HIV and suggest that other qualitative features of the CD8+ T-cell response may differentiate pts capable of immune-mediated restriction of HIV replication.