Fatal infection in mice after injection of immunosuppressive serum fractions from surgical patients

Abstract

Following surgical or accidental trauma many patients show suppression of cellular immunity. In this investigation sera from severely burned patients and patients undergoing aortic aneurysm repair were studied. Sera shown to suppress phytohaemagglutinin-induced blastogenesis of normal human lymphocytes were fractionated using ion exchange and G25 Sephadex chromatography. Suppressive activity was largely confined to a low molecular weight (LMW) fraction and was dose dependent. LMW fractions of normal sera had no significant suppressive activity. The purpose of this study was to test the causal relationship between immunosuppressive serum and decreased resistance to bacterial infection. Listeria monocytogenes infected mice were used as an in vivo model to test suppression of cellular immunity. Injection of LMW fractions of suppressive sera significantly increased mortality in these mice, but had no effect on non-infected mice. There was good correlation between the in vitro and in vivo effects of the suppressive fractions. These results suggest that a circulating factor in the serum of injured patients suppresses cellular immunity and may be responsible for impaired resistance to infection.

The Release of Immunosuppressive Factor(s) in Young Males Following Exercise

“…An animal model has long been used for examining the human immune function, and is acceptable for testing circulating immunosuppressive polypeptide in vitro [11]. The testing procedure has been described previously [11].…”

“…The testing procedure has been described previously [11]. For each blood sampling, venous blood (5 mL) was drawn from the antecubital vein using a venous puncture with subjects in a sitting position, and the blood was allowed to clot at room temperature.…”

“…This study was designed to examine the generation of immunosuppressive factors in response to exercise. Since the model of lymphocyte proliferation induced by Con A in mice has been well established for testing the circulating immunosuppressive polypeptide of humans in clinical situations [11], the generation of immunosuppressive factors in humans in response to exercise was revealed by comparing the effects of pre- and post-exercise human serum on the Con A-induced lymphocyte proliferation in the mice model.…”