TCRab/Vb2 Antibody [TCR-3]

The monoclonal antibody TCR-3 precipitates a CD3-associated heterodimer of Mr 88 kDa (two bands of Mr 48 kDa and 40 kDa upon reduction) on chicken peripheral blood T cells. Deglycosylation of the heterodimer yields two polypeptides of Mr 34 kDa and 31 kDa. In the chicken, two distinct subpopulations of alphabeta T cells appear in the thymus subsequent to the appearance of gammadelta T cells. These subpopulations, originally denoted as TCR-2 and TCR-3, arise sequentially in the thymus during ontogeny and are now known to represent two distinct Vbeta families, Vbeta1 and Vbeta2, respectively. The TCR-3 monoclonal antibody reacts with approximately 9% of thymocytes, 15-25% of blood mononuclear cells, and 13% of splenocytes young adult chickens. Two-color immunofluorescence has revealed that the TCR-3+ thymocytes include CD4+CD8-, CD4-CD8+, CD4+CD8+, and CD4-CD8- subpopulations. The TCR-3+ thymocytes can be separated into two subsets. One subset is characterized by relatively low levels of expression of the TCR-3/CD3 complex and most of the cells in this subset are CD4+CD8+. Cells in the other subset express TCR-3/CD3 in higher density and are either CD4+CD8- or CD4-CD8+, corresponding to the more mature medullary subset of thymocytes. The TCR-3+] cells in the blood and spleen express relatively high levels of the TCR-3/CD3 receptor complex and are “single positive” with CD4+CD8- cells being four times more frequent that the CD4-CD8+ cells (~ 80% CD4+ vs ~ 20% CD8+) .