Postburn immunosuppression in an animal model: monocyte dysfunction induced by burned tissue

We studied cell-mediated immunity (CMI) in burned mice using an assay that involves the induction of contact sensitivity to dinitrofluorobenzene (DNFB). Subsequent painting of the ears with DNFB and measurement of ear swelling with calipers is a sensitive and quantifiable assay for CMI. Results may be expressed as mean ear swelling (MS) in units of 10(-4) inches +/- 2 standard errors of the mean. CMI was severely depressed in burned mice over a 2-week period following burn (control MS 48.3 +/- 1.0, 14 days after burn 29.0 +/- 1.0, P less than 0.01). Immediate postburn eschar removal resulted in avoidance of immunosuppression (MS 41.5 +/- 1.0, P less than 0.01) while transfer of burned tissue subcutaneously into unburned mice resulted in severe immunosuppression (MS 33.2 +/- 2.6, P less than 0.01). CMI was restored by intravenous infusion of peritoneal macrophages from unburned mice (MS 41.4 +/- 2.2), but not by infusion of lymphocytes or of macrophages taken from burned mice. This model should prove useful for further study of burn injury-induced immunosuppression.