T Cell Receptor Variable Gene Expression: Analysis in Ragweed-Sensitive Patients during Allergen Exposure

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Four monoclonal antibodies (MAb) to V region determinants of the alpha/beta-chain of the T cell antigen receptor (TCR) were used, by cytofluorography, to detect discrete populations of peripheral blood T cells (PBT). Together they identify 10-15% of circulating CD3+ T cells. Each MAb is known to detect specific V regions of the beta-chain. Thus V beta 5 gene products are recognized by MAb C37, V beta 6 by OT145, V beta 8 by Ti3a, and V beta 12 by MAb S511. In previous studies, we found that the percentages of PBT detected by these MAb show little variation over time in normal individuals. In order to determine if there is a change in TCR V gene usage during an immune response to an environmental antigen, 12 atopic patients with known ragweed sensitivity by history and skin test were followed for a 6-month period encompassing the ragweed season. No shifts in V gene usage that could be correlated with the ragweed season were consistently observed. The patients could be arbitrarily divided into two groups: in group I little variation over time was observed in the T cell populations identified by the MAb used, while group II was characterized by marked variation of the same T cell populations over time. In group II individuals, the population of Ti3a+ T cells showed the most variation over time. Failure to observe shifts in PBT subpopulations, identified by expression of different TCR V regions, during exposure to an allergen to which an IgE response has been made may mean that such shifts do not occur or that they occur primarily at the tissue site of antigen exposure and not in the peripheral circulation or that they occur in T cell subpopulations not identified by the reagents used.