Abstract
TCR/CD3 complex is composed of the disulfide-linked TCR-αβ heterodimer that recognizes the antigen as a peptide presented by the MHC, and non-covalently paired CD3γε- and δε-chains together with disulfide-linked ζ-chain homodimers. The CD3 chains play key roles in T cell development and T cell activation. In the present study, we found nor or extremely lower expression of CD3ε in head- and trunk-kidney lymphocytes by flow cytometric analysis, while CD3ε was expressed at the normal level in lymphocytes from thymus, spleen, intestine, gill, and peripheral blood. Furthermore, CD4-1+ and CD8α+ T cells from kidney express Zap-70, but not CD3ε, while the T cells from other tissues express both Zap-70 and CD3ε, although expression of CD3ε was low. Quantitative analysis of mRNA expression revealed that the expression level of T cell-related genes including tcrb, cd3ε, zap-70, and lck in CD4-1+ and CD8α+ T cells was not different between kidney and spleen. Western blot analysis showed that CD3ε band was detected in the cell lysates of spleen but not kidney. To be interested, CD3ε-positive cells greatly increased after 24 h in in vitro culture of kidney leukocytes. Furthermore, expression of CD3ε in both transferred kidney and spleen leukocytes was not detected or very low in kidney, while both leukocytes expressed CD3ε at normal level in spleen when kidney and spleen leukocytes were injected into the isogeneic recipient. Lower expression of CD3ε was also found in kidney T lymphocytes of goldfish and carp. These results indicate that kidney lymphocytes express no or lower level of CD3ε protein in the kidney, although the mRNA of the gene was expressed. Here, we discuss this phenomenon from the point of function of kidney as reservoir for T lymphocytes in teleost, which lacks lymph node and bone marrow.
Highlights
The antigen receptor complex on T-cell (TCR/CD3) consists of the disulfide-linked TCR-αβ heterodimer that recognizes the antigen as a peptide presented by the MHC, and non-covalently paired CD3γε- and δε-chains together with disulfide-linked ζ-chain homodimers
We found that CD4-1+ and CD8α+ T lymphocytes from head-and trunk-kidney express Zap-70, but not CD3ε, while T lymphocytes from tissues except kidney express both CD3ε and Zap-70
Western blot analysis showed that the antibody is specific to native ginbuna CD3ε present in thymus and spleen since positive band was detected at 20–25 kDa as expected molecular weight (Figure S2 in Supplementary Material) and disappeared after adsorption with the recombinant ginbuna CD3ε (rgCD3ε) (Figure S3 in Supplementary Material)
Summary
The antigen receptor complex on T-cell (TCR/CD3) consists of the disulfide-linked TCR-αβ heterodimer that recognizes the antigen as a peptide presented by the MHC, and non-covalently paired CD3γε- and δε-chains together with disulfide-linked ζ-chain homodimers. Ahmadi et al [6] showed that co-transfer of CD3 and TCR genes into primary murine T cells enhanced TCR expression and antigenspecific T-cell function in vitro. Downregulation in the expression of CD3 chains in T cells and impaired immune responses have been reported in patients with malignant and/or inflammatory autoimmune diseases [7–9]. These reports indicate that the critical roles of CD3 chains in mature T cell activation as well as in T cell development and signaling
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