T cell receptor gamma delta repertoire in HIV-1-infected individuals.

While V gamma 9/V delta 2 cells dominate among peripheral blood gamma delta T cells in healthy adults, the majority of gamma delta T cells in most HIV-1-infected individuals express V delta 1. We asked whether these elevated levels of V delta 1 T cells were due to clonal expansion. Three-color flow cytometry with monoclonal antibodies against V gamma 2/V gamma 3/V gamma 4, V gamma 4 and V gamma 9 was used to investigate V gamma usage in 27 patients with elevated numbers of V delta 1 T cells. While the relative proportion of V gamma 9 cells among gamma delta T cells was significantly reduced in HIV-1+ individuals (10 +/- 11% vs. 80 +/- 17%, p < 0.001), the fraction of gamma delta T cells using V gamma 5 or V gamma 8 was significantly increased (54 +/- 15% vs. 7 +/- 11%, p < 0.001). In 1 patient, 76% of the V delta 1 cells expressed V gamma 2 or V gamma 3, suggesting clonality of the V delta 1 population. In line with this assumption, analysis of the V delta 1-J delta junctional regions by reverse transcription-polymerase chain reaction (RT-PCR) resulted in products of only one junctional length, as demonstrated by electrophoresis on denaturing gels, and 12 out of 16 (75%) in-frame junctional sequences were identical in this patient. In other HIV-1+ patients, RT-PCR resulted in products of several distinct sizes, also indicating a highly restricted repertoire. After sequencing the V delta 1-J delta junctional regions of 3 additional patients, we found repeated but patient-specific in-frame junctions accounting for 10-30% of the sequenced clones. However, limited V delta 1-J delta junctional diversity was also seen in healthy donors. RT-PCR products from 10 healthy individuals resulted in distinct bands on denaturing gels. In 1 of them exhibiting a single prominent band, 10 out of 17 (58%) sequenced junctions were identical. Two other healthy donors displayed 2/14 and 5/18 identical junctional sequences, respectively. Taken together, our results reveal significant alterations of V gamma usage in HIV-1+ patients, while the V delta 1 junctional repertoire is similarly restricted in HIV-1+ and HIV-1- individuals. Therefore, these data argue against an obligatory clonal expansion of V delta 1-expressing cells during HIV-1 infection.