Temporal relationships among immunologic alterations in a guinea pig model of thermal injury.

Temporal relationships among various humoral and cellular alterations of host defense mechanisms were investigated in a guinea pig model of thermal injury during three weeks after burning. Reduction in serum concentration of C3 and fixation of C3 on Pseudomonas aeruginosa, presence of activated C3 in plasma, and elevations in levels of 6-ketoprostaglandin F1 alpha and thromboxane B2 in wound fluid were observed at 3-6 hr after burning. These alterations were accompanied by reduction in intrinsic bactericidal activity of polymorphonuclear neutrophils (PMNs) against P. aeruginosa, suppression of bactericidal activity of PMNs by serum, and decreased blood clearance of P. aeruginosa. All parameters returned to normal values by seven to nine days after burning. Proliferative responses of splenic lymphocytes to T cell mitogens were depressed at four days after burning and were maximally reduced at eight days. These data support the concept that there is a continuum of immunologic alterations resulting from thermal injury and that consumption of complement and increase in arachidonic acid metabolism are early events.