Early Alterations in HLA Class II Expression and Response to Tetanus Toxoid by Peripheral Blood Monocytes from Patients with Injury from Burns or Trauma

Abstract

Sepsis is a major complication of injuries from burn and trauma [1]. CD4+ lymphocytes, which play a prominent role in the elimination of microbes from the host, require human class II antigen (HLA)-bearing accessory cells for activation and proliferation [2]. Monocytes that are HLA class II+ can serve as accessory cells by internalizing and processing antigen [2]. The antigen is then transported to the membrane of the monocyte, where it is found in association with monocyte HLA class II antigens [2]. CD4+ lymphocytes recognize the antigen/HLA complex and proliferate [2]. The efficiency of antigen processing and presentation is dependent on the percentage of cells that bear HLA class II molecules and the density of HLA class II molecules on the surfaces of cells [3]. We were interested, therefore, in determining whether monocytes from individuals injured by burns or trauma had altered expression of class II which affected accessory function. We measured the expression of HLA class II molecules on monocytes within 24 h of injury and correlated the results with proliferation of lymphocytes to a soluble antigen, tetanus toxoid, in a monocyte-dependent response.

R.A.S.G. was supported by Grant #GM07032-05 from the National Institute of Health.