Distinct gene expression in human Vd1 and Vd2 gd T cells following non-TCR agonist stimulation

The two major human gd T cell subsets, Vd1 and Vd2, display differences in tissue tropism and agonist responses, but we have little insight into global differences that may exist at the gene expression level. This is due to the small numbers of these cells that can be obtained from healthy donors, which limit comprehensive, comparative gene expression analyses. We established a culture method that expands Vd1 and Vd2 cells from the same PBL preparation to levels sufficient for sorting and microarray analysis. Although the subsets were expanded identically (anti-TCR mAb, plus IL-15), 392 and 614 genes were identified, which were differentially expressed in the two subsets, from two donors, respectively. Approximately 4,500 genes changed in both subsets following PMA/ionomycin treatment; about 50% of these genes were subset-specific. Both subsets responded to a crude LPS preparation, but only 6% of the responsive genes were the same. The differentially expressed genes were consistent with Vd2 cells being more inflammatory and Vd1 cells having more of a regulatory phenotype. Both subsets expressed transcripts encoding an array of innate and NK cell receptors, supporting the relationship of gd?T cells to the innate immune system. Our results show that circulating Vd1 and Vd2 subsets in humans have considerable, inherent differences in gene expression following treatment with non-TCR agonists, supporting unique functional roles for these cells in vivo. Keywords: cell type comparison To analyze global gene expression differences between Vd1 and Vd2 gd T cells, 12 Affymetrix Human Genome U133A 2.0 chips were run. 2 replicate sets of 6 chips from 2 donors were run; each set of six chips consisted of 3 chips for Vd1 cells and 3 chips for Vd2 cells. The 3 chips for each subset consisted of cells treated with PBS, LPS, or PMA/ionomycin for 4 hours just prior to RNA extraction.