No abstract

We have analyzed the expression of the activation antigen CD69 on normal human T cells by flow cytometry following stimulation with mitogens and recall antigen. These data were compared to parallel studies assessing the proliferative response using the 3H‐thymidine (3H‐TdR) incorporation assay. Three different mitogens (PHA, ConA, and CD2/CD2R) induced maximal expression of CD69 at 24 h, which remained stable throughout the 72 h culture period. The mitogen‐stimulated cells initiated DNA synthesis as determined by the 3H‐TdR assay (72 h) while nonstimulated cells failed to upregulate CD69 or incorporate 3H‐TdR. We next compared T cell CD69 expression (n = 12) following stimulation with either CD2/CD2R (5μg/ml) or the recall antigen, tetanus toxoid (1:1500). Cell proliferation was determined by the 3H‐TdR assay at 72 h (CD2/CD2R) or 120 h (tetanus toxoid). Evaluation of CD69 expression at 6 h predicted CD2/CD2R but not tetanus responder status as defined by 3H‐TdR incorporation. However, when 4 known tetanus responders (3H‐TdR) were evaluated over time, it was found that at 48 h the fluorescence intensity (of CD69) on tetanus‐stimulated CD3+ cells increased markedly compared with nonstimulated cells (range of increase 43–850%). One individual whose cells failed to respond to tetanus toxoid (3H‐TdR and CD69) did respond normally to CD2/CD2R. These observations suggest that flow cytometric evaluation of T cell CD69 expression following mitogen (6 h) or antigen (48 h) stimulation may provide an accurate screen of T‐cell responsiveness in normals. © 1996 Wiley‐Liss, Inc.