Determination of expression pattern of specific receptors on CD4- and CD8-positive T cells at the onset of severe sepsis. Peripheral blood was collected from patients within 24 hours of the onset of severe sepsis and from normal controls and stained for the indicated markers. The percent positive relative to isotype control staining was determined. Fluorescence intensity was quantified by calculation of MESF values as described in the methods. Horizontal lines indicate the mean value. P values were calculated by a non-parametric 2-tailedMann-Whitney U-test. MESF, molecules of equivalent soluble fluorochrome.