Ontogeny of expression of UCHL1 antigen on TcR‐1+ (CD4/8) and TcRδ+ T cells

The frequency of blood mononuclear cells expressing the 180-kDa splice variant of the common leukocyte antigen identified by the UCHL1 monoclonal antibody (a characteristic of post-thymic cells which have been through a cycle of stimulation) rose in a logarithmic relationship to age between birth and 16 years. At birth only a low frequency of CD4+ (negative for CD 25) and no CD8+ T cells expressed UCHL1. The subsequent increase in UCHL1 expression occurred in parallel on T cells expressing alpha/beta receptors and gamma/delta receptors, suggesting that these subsets participated in post-thymic proliferation in proportion to their numbers in blood. The frequency of UCHL1 expression on CD8 cells was 5-15% less than on CD4 cells.