Expression of 'pan T cell' cell surface antigens by T
lymphocytes occurs in the following sequence: CD7 (early
prothymocyte); CD2 (midprothymocyte); CD5 (immature
thymocyte), cytoplasmic CD3 (immature and common
thymocyte) and CD3 (mature thymocyte).2,6 This is
followed by coexpression (common thymocyte) and then
distinct expression (mature thymocyte) of CD4 (inducer)
and CD8 (suppressor/cytotoxic) cell surface antigens.2,6
Once expressed, the CD7, CD2, CD5 and CD3 antigens
with either CD4 or CD8 are coexpressed continuously
throughout the remainder of T lymphocyte differentiation
including both the resting and the activated mature
peripheral blood or lymphoid tissue T lymphocyte.