Progressive increase of CD7‐ T cells in human blood lymphocytes with ageing
CD7 is one of the major surface antigens expressed very early during T cell ontogeny. Lack of CD7 expression on mature T cells is regarded as a classical feature of malignant T cells in certain forms of cutaneous T cell lymphoma. Previously, we identified a CD7‐ subset of peripheral blood T lymphocytes in normal human individuals. In this study we determined the portion of CD7‐ T cells in the peripheral blood of healthy volunteers ranging in age from 8 months to 90 years (n= 85) and in cord blood of full‐term infants (n= 14), Furthermore, this CD7‐ subset was characterized in detail by the use of MoAbs and three‐colour flow cytometry. In cord blood no CD7‐ T cells could be detected. After birth, percentage and absolute number of CD7‐ T cells increased with age. Independently of age, most CD7‐ CD3+ cells belonged to the CD4+ subpopulation. Focusing on the latter we could demonstrate the predominance of the CD45RO+CD45RA‐ phenotype in the CD7‐ subset. Furthermore, CD7‐ T cells contained a higher number of cells expressing activation markers and the CD57 antigen, but a reduced number of CD62L+ cells in comparison with CD7+ T cells.