CD3 proteins may have redundant as well as specific contributions to the intracellular propagation and final effector responses of TCR-mediated signals at different checkpoints during T cell differentiation. However, to date, the relative role that each CD3 chain plays in signaling is controversial. The patients with CD3γ deficiency can present with different clinical findings despite having the same homozygous mutation. In order to examine the roles of CD3γ chain in TCR signaling, CD3γ can propagate a number of signals through the remaining invariant chains, likely the homologous CD3δ chain, which replaces it at the mutant TCR.
Caption: Immunochemical staining of human CD3D in human spleen with mouse Mab (15 µg/mL, formalin-fixed paraffin embedded sections). Positive staining was localized to membrane of T cells.