Serial Analysis of Gene Expression in Circulating γδ T Cell Subsets Defines Distinct Immunoregulatory Phenotypes and Unexpected Gene Expression Profiles

Abstract

Gene expression profiles were compared in circulating bovine GD3.5+ (CD8−) and GD3.5− (predominantly CD8+) γδ T cells using serial analysis of gene expression (SAGE). Approximately 20,000 SAGE tags were generated from each library. A comparison of the two libraries demonstrated 297 and 173 tags representing genes with 5-fold differential expression in GD3.5+ and GD3.5− γδ T cells, respectively. Consistent with their localization into sites of inflammation, GD3.5+ γδ T cells appeared transcriptionally and translationally more active than GD3.5− γδ cells. GD3.5− γδ T cells demonstrated higher expression of the cell proliferation inhibitor BAP 37, which was associated with their less activated gene expression phenotype. The immune regulatory and apoptosis-inducing molecule, galectin-1, was identified as a highly abundant molecule and was higher in GD3.5+γδ T cells. Surface molecules attributed to myeloid cells, such as CD14, CD68, and scavenger receptor-1, were identified in both populations. Furthermore, expression of B lymphocyte-induced maturation protein, a master regulator of B cell and myeloid cell differentiation, was identified by SAGE analysis and was confirmed at the RNA level to be selectively expressed in γδ T cells vs αβ T cells. These results provide new insights into the inherent differences between circulating γδ T cell subsets.

Porcine γδ T Lymphocytes Can Be Categorized into Two Functionally and Developmentally Distinct Subsets according to Expression of CD2 and Level of TCR

“…The conclusion that CD2 + and CD2 2 gd T cell are two lineages is also supported by the finding that they differ in expression of TCRg-chains (8). Furthermore, findings in cows show that these two lineages differ in expression of non-TCRgd cell Ags WC1 and GD3.5, in expression of cell adhesion molecules, and in ability to infiltrate into inflammatory sites (15,23). In any case, these two lineages are equally capable of immune responses because analysis of CDR3 length polymorphism showed equal diversification of Vd1 with no restriction of TCR repertoire.…”

“…Evidence that TCRgd is expressed differently can be found in other reports (15,16), but to our knowledge this phenomenon was never studied in detail. Porcine TCRgd med and TCRgd hi cells are distributed differently among CD2/CD8 subsets, which are know to home differentially into various lymphatic tissues.…”

“…This unequal distribution throughout different tissues is probably connected to their differential expression of Lselectin and E-selectin ligand (23). Moreover, another work in cows showed that CD8 +/2 gd T cell subpopulations differ in expression of many other molecules such as galectin-1, prolactin, IgE-dependent histamine-releasing factor, epidermal growth factor, IL-10 or Gro-g, IL-1, CD44, CD18, and MHC class I (15). Interestingly, although authors of these findings did not study differential level of TCRgd expression, they noted that CD8 + gd T cells express lower levels of TCR.…”

“…However, it is known that TCR can be expressed on gd T cells in two densities: medium and high (15,16). Unfortunately, the relevance of TCRgd med/hi expression was never studied in more detail.…”

Tyrosine phosphorylation of scavenger receptor cysteine‐rich WC1 is required for the WC1‐mediated potentiation of TCR‐induced T‐cell proliferation

“…A majority of these gd T cells in ruminants bear the glycoprotein lineage marker Workshop cluster 1 (WC1) on their surface. Based on the profiles of their gene expression, WC1 1 gd T cells of cattle represent the inflammatory population, whereas WC1 À gd T cells are regulatory cells [2,3]. WC1, a member of the scavenger receptor cysteine-rich (SRCR) superfamily, is categorized into group B along with CD5, CD6, and CD163, based on the organization of cysteine residues in its extracellular SRCR domains [4].…”