Mitogen-induced T-cell CD69 expression is a less sensitive measure of T-cell function than [(3)H]-thymidine uptake

The most widely used in vitro measure of T-cell function has been the assessment of mitogen induced proliferation by [(3)H]-thymidine incorporation. Mitogens also induce T-cell surface expression of a number of molecules associated with activation, including CD69. Recent reports have suggested that flow cytometric analysis of CD69 expression may be a simpler and faster means of measuring T-cell function. Most studies have been on normal subjects, and the sensitivity of CD69 expression as an in vitro measure of clinical immunodeficiency remains unknown. We address this issue by concurrently measuring mitogen-stimulated T-cell CD69 expression and [(3)H]-thymidine incorporation in a normal population and five immunocompromised patients negative for the human immunodeficiency virus (HIV). All patients had recurrent infections and had known causes of immunodeficiency. Whole blood cultures were setup to measure phytohaemagglutinin A (PHA)- and superantigen staphylococcal enterotoxin B (SEB)-induced CD69 expression at 5, 24, and 72 h, and [(3)H]-thymidine incorporation at 72 h. All immunodeficient patients had lower than normal PHA responses and 3 of 4 had low SEB responses. However in 7 out of 8 of the patient tests, mitogen-induced T-cell CD69 expression was within the normal range. Similar results were found with CD4(+) T-cell CD69 expression. This study indicates that measurement of mitogen-induced T-cell CD69 expression lacks sensitivity in determining T-cell dysfunction in HIV-negative immunodeficient patients.