Clinical significance of the soluble interleukin-2 receptor as a putative systemic nutritional index in the elderly*

Abstract

Background: The clinical significance of a slight increase in serum soluble interleukin-2 receptor (sIL2R) concentration in the stable elderly was investigated. Methods: The subjects consisted of 35 residents of nursing homes with physical impairment as a sequela to cerebral infarctions, who had no inflammatory conditions, and were not receiving anodyne or immunological treatment. They were divided into two groups: 24 subjects without overt or suspected malignancy (NC) and 11 with a history of malignancy (CA). Serological screening with measurement of sIL2R concentrations was performed and numbers of lymphocytes with CD4 and CD8 markers were determined. The NC group was subdivided into control subjects (n = 15, sIL2R < = 883 U/mL) and subjects demonstrating elevated concentrations of sIL2R (n = 9, NH), as in a previous study. Results: Between the NH and control groups, differences were found in serum concentrations of albumin, blood urea nitrogen, total cholesterol concentration, Pettigrew's prognostic nutritional index (PNI) and activities of daily living score, but not in age or sex. Factor analysis in the NC group showed serum creatinine and blood urea nitrogen concentrations to be correlated positively, and serum albumin, total cholesterol concentrations, activities of daily living score, and PNI to be correlated negatively with sIL2R. Differences were found in sIL2R, albumin, total protein, total cholesterol, β-lipoprotein and PNI between the CA and control groups, but no correlations among these parameters were found in the CA group. There was no difference in the rate of positive test results for rheumatoid factor between the NC and CA, or control and NH groups. The survival rate of control subjects over 24 months was better than that of NH subjects, but not that of CA subjects. Conclusion: Our results suggest that a slight increase in the concentration of sIL2R is related to subclinical systemic deterioration, especially regarding nutrition, with a plausible connection to prognosis, in stable elderly patients without malignancy.