Association between reduced human leukocyte antigen (HLA)-DR expression onblood monocytes and increased plasma level of interleukin-10 in patients with severe burns

Severe thermal injury causes an immune dysfunction which includes a decreas e of monocyte human leukocyte antigen DR (HLA-DR) expression. Interleukin-1 0 exerts a negative influence on this parameter in vitro. In this study we determined the prognostic value of reduced monocyte HLA-DR expression with regard to infectious complications, and the in vivo association between mon ocyte HLA-DR and plasma interleukin-10 concentration. Both quantities were measured serially in 19 patients with severe burns. HLA-DR expression was d etermined by direct immunofluorescence on a flow cytometer, and interleukin -10 was measured by ELISA. After burn trauma the percentage of HLA-DR expre ssing monocytes fell markedly (median: 53 % at day 2, 36 % at day 4, 31 % a t day 7, 28 % at day 9, 35 % at day 12, and 42 % at day 14; compared to 93 % for healthy volunteers). Moreover, patients who became septic showed lowe r monocyte HLA-DR expression than non-septic patients; the differences were significant at day 2 (p < 0.01) and day 7 (p < 0.05). Plasma concentration s of interleukin-10 increased after thermal injury (median: 40 ng/l at day 2, 43 ng/l at day 4, 77 ng/l at day 7, 120 ng/l at day 9, 63 ng/l at day 12 , and 82 ng/l at day 14). Individual HLA-DR expression and interleukin-10 c oncentration were negatively correlated, the association reaching statistic al significance at day 4 (p = 0.006) and day 7 (p = 0.031). Thus, after sev ere burn injury monocyte HLA-DR expression has prognostic value and is nega tively associated with interleukin-10 plasma concentration.