Selective usage of defined TCRBV genes in response to filarial antigens

Biased TCR Repertoire in Infiltrating Lesional T Cells in Human Bancroftian Filariasis

To investigate the hypothesis that T cells recognizing specific Ags localize to the site of disease activity in human bancroftian filariasis, we have compared the repertoire of TCR Vβ gene segments in lesions vs blood in individual patients by RT-PCR ELISA. Vβ14 and Vβ24 were overrepresented (5% greater in tissue compared with PBMCs and/or tissue/PBMC ratios in the highest 5% of all tissue/PBMC ratios for all Vβs for all subjects) in 50% and 40% of study subjects, respectively. Overrepresentation of these two Vβs did not occur in any control subject. In comparing three patient groups, the proportion of individuals meeting at least one criterion for Vβ14 overrepresentation was shown to increase in tandem with our current concepts of disease progression (asymptomatic filariasis = 25%; clinical filariasis with active infection = 60%; clinical filariasis without active infection = 71%). In 6 of the 10 individuals with Vβ14 overrepresentation, Vβ14 represented >20% of the entire lesional Vβ repertoire. All but one of the 20 study subjects had at least one Vβ gene segment that was overrepresented in tissue compared with PBMCs. Only a small number of Vβs, usually three or less, were overrepresented in any single filariasis patient. However, in the same tissue, no differences between patient groups were found when IFN-γ, TNF-α, IL-4, IL-5, and IL-12 mRNA expression were examined. Taken together, these findings suggest that, in principle, in essentially all patients, whether with subclinical or with clinical filariasis, distinct and limited T cell populations are concentrated in affected tissue.