T-lymphocyte subsets in acute illness.

Abstract

OBJECTIVES: To determine the range of T-lymphocyte subsets (CD4, CD8, and CD4/CD8 ratios) in acutely ill, hospitalized patients and to determine whether these concentrations correlate with illness severity, survival rate, or immunodepression. DESIGN: Cross-sectional study, comparing Acute Physiology and Chronic Health Evaluation II (APACHE II) scores and the calculated, disease-specific, predicted mortality rate with T-lymphocyte subsets. SETTING: Urban county hospital intensive care unit (ICU), serving as the designated trauma center. PATIENTS: One hundred two consecutively admitted ICU patients (72 medical and 30 surgical). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patient clinical data, APACHE II scores, and their associated predicted mortality rate were recorded. Blinded human immunodeficiency virus (HIV) and lymphocyte testing was performed on samples from all patients on ICU admission. Despite only three (2.9%) of 102 patients testing positive for HIV antibodies, 41% (42/102) of patients had CD4 concentrations of < 400 cells/microL, and 29% (29/102) had CD4 concentrations of < 300 cells/microL. Mean CD8 concentrations were even lower, compared with normal laboratory values, resulting in a slight increase in CD4/CD8 ratios, although 16% (16/102) of patients had a CD4/CD8 ratio of < 1. CD4 counts were linearly related to total lymphocyte concentrations (Pearson correlation coefficient = 0.948), but no relationship was found between total lymphocyte or lymphocyte subset counts and APACHE II score, predicted mortality rate, or survival rate. CONCLUSIONS: Acute illness alone, in the absence of HIV infection, can be associated with profound decreases of T-lymphocyte populations. This problem is unpredictable and does not correlate with severity of illness, predicted mortality rate, or actual mortality rate. No conclusions regarding HIV serostatus or survival can be made based on single measurements of T-cell concentrations in acutely ill hospitalized patients.