Inadequate interleukin-2 synthesis and interleukin-2 messenger expression following thermal and mechanical trauma in humans is caused by defective transmembrane signalling

Abstract

The study was performed to further elucidate the mechanisms of dysfunctional T-cell activation following extensive burn and mechanical injuries. The major regulatory level of interleukin-2 (IL-2) release under stressful conditions was determined via parallel analysis of IL-2 messenger RNA (mRNA) expression and IL-2 protein synthesis in mitogen-stimulated peripheral blood mononuclear cell (PBMCs) cultures on consecutive days postinjury. Furthermore, we wanted to scrutinize if inadequate lymphokine production after trauma is possibly a result of defective transduction of extracellular signals to the T-cell nucleus. Fourteen patients (11 men, 3 women, average age 38 +/- 6 years, Injury Severity Score 34 +/- 2) were included in the study. The PBMCs were isolated on days 1, 3, 5, 7, and 10 and stimulated either with the mitogen phytohemagglutinin (PHA) alone or in combination with the protein kinase C (PKC) activator phorbol myristate acetate (PMA). The protein release was examined via bioassay (human con-A blasts) from the supernatants, and the cellular RNA was indicated by radioactive hybridization with the specific complementary DNA (cDNA) after Northern blotting. The IL-2 protein synthesis generated in PHA-stimulated PBMC cultures following trauma, compared with that in controls (0.62 +/- 0.04 U/mL) was persistently and significantly depressed during the observation time with a 57% inhibition on day 10-identical with that on day 1. The Northern blot analysis of IL-2 mRNA expression in the lysates of PHA-stimulated cell cultures after trauma could not detect any mRNA signal for IL-2, in contrast to the control cells.(ABSTRACT TRUNCATED AT 250 WORDS)