OBJECTIVETo study dynamics of T lymphocyte subsets in severe acute respiratory syndrome (SARS).

METHODSSequential anti-coagulated blood samples were collected from 46 cases of SARS patients during the 1st week, the 2nd week, the 3rd-5th week and the 8th-12th week after the infection. T lymphocyte subsets including CD3+CD4+ cells, CD3+CD8+ cells, naive CD4+ cells (CD4+CD45RA+CD62L+) and activated CD8+ cells (CD8+CD38+) were detected by 3-color flow cytometry. Fifty-six normal healthy blood donors were also detected as normal controls.

RESULTSCompared with the results of normal controls, both of the percentages of CD4+ cells and CD8+ cells of SARS patients were in normal levels during the 1st week, but the cell counts decreased significantly to (306 +/- 140)/mm3 and (270 +/- 143)/mm3, respectively. The cell count of naive CD4+ subset also remarkably decreased to (96 +/- 49)/mm3, and the percentage of CD8+CD38+ subset was higher than that of normal controls [(59.3 +/- 12.6)% vs (44.9 +/- 12.5)%]. During the 3rd-5th week, the CD8+ cell count and the percentage of CD8+CD38+ subset reached normal values, which were (581 +/- 356)/mm3 and (40.1 +/- 17.6)%, respectively. During the 8th-12th week, the cell counts of CD4+ cell [(578 +/- 193)/mm3] and naive CD4+ subset [(176 +/- 64)/mm3] were still less than those of normal controls, while compared with those of the 1st week, the increments were remarkable.

CONCLUSIONST lymphocytes of SARS patients decreased dramatically but could be obviously resumed in a short time. It will take more than 8-12 weeks for CD4+ cell and naive CD4+ subset to reach to normal levels.