RESUMEN
<p><b>OBJECTIVE</b>To study abnormal changes of T lymphocyte and its activated subsets in severe acute respiratory syndrome (SARS) patients.</p><p><b>METHODS</b>Flow cytometer with multi-color flouroscence and hematology analyzer were used to detect the expression of T lymphocyte and its activated a subsets in 240 SARS patients including 50 cases of critical type and 190 cases of common type.</p><p><b>RESULTS</b>Statistical analysis by means of SAS software showed that there was significant decrease in absolute counts (AC) of T lymphocyte and its subsets in SARS patients when compared with normal people, while percentages (PC) of CD3+CD25+ and CD3+ HLA-DR+ subsets were increased markedly. Compared with common type, there was significant decrease in absolute counts of critical type of T lymphocyte, CD4+, CD25+CD3+, CD28+CD4+, and CD95+CD4+subsets. The ACs of T lymphocytes including CD4 and CD8 subsets in different phases were as below: III > II > I. The ACs of subsets involved in activation such as CD3+ HLA-DR+/lym, CD3+CD25+/lym, CD28+CD4+/CD4, CD28+CD8+/CD8, and CD38+CD4+/CD4 all were highest in group III. In addition, the AC and PC of CD95+CD4+/CD4 and CD95+CD8/CD8 subset in group III were highest while group I was lowest.</p><p><b>CONCLUSIONS</b>With depressing cellular immunity, the activation of T lymphocytes were suppressed obviously in SARS patients, especially for critical patients.</p>