FIGURE 1.

Ex vivo analysis of HIV p24-tetramer⁺ CD4 T cells in different patient groups. Representative examples are shown for a long-term nonprogressor (A, patient LT11), a patient off therapy (B, patient AC20), and a patient under ART (C and D, patient AC03). Freshly isolated PBMCs were enriched for CD4 T cells and labeled with control or HIV p24 tetramers (Tet), Abs to CD4, CCR7, and CD45RA, and exclusion markers CD8, CD14, CD16, CD19, CD56, and 7AAD. (CCR7 and CD45RA Abs were omitted for the staining done on LT11.) FACS plots show CD4 vs tetramer staining for the CD4⁺CD8⁻CD14⁻CD16⁻CD19⁻CD56⁻, and 7AAD⁻ population, with the frequency of tetramer⁺ CD4 cells (per 10⁶ CD4 T cells) indicated in the right-hand corner. The tetramers comprised three different DR alleles, DRB1*0401, DRB5*0101, and DRB1*0101, loaded with four different HIV p24 peptides (p24-1, p24-2, p24-3, or p24-4) or control peptides (CLIP for DRB1*0101, annexin II for DRB5*0101 and DRB1*0401). CD4 T cells specific for the p24-4 peptide were identified in patients with different DR alleles using tetramers of DRB1*0401 (A and D), DRB1*0101 (B), and DRB5*0101 (C) loaded with this HIV peptide. HIV p24-positive CD4 T cells were detected in patients from all three groups and at the highest frequency in the long-term nonprogressor.