The purpose of this study was to assess the influence of thermal injury and the inflammatory process on chemotactic responses of neutrophils to four attractants (N-formyl-methionyl-leucyl-phenylalanine, the complement fragment C5a, interleukin-8, and leukotriene B4) under agarose, expression of Mac-1 (CD11b/CD18) adherence receptors on the cell surface, and polymerization of actin in the cell cytoplasm. Circulating neutrophils were isolated from peripheral blood, and exudate neutrophils from fluid collecting under two different wound dressings applied to abrasion sites of healthy subjects and to skin graft donor sites of patients with burns. Burn injury reduced the chemotactic responses of circulating neutrophils to all four attractants, suggesting a "global" defect in chemotactic function. Patient-exudate neutrophils collected under Tegaderm exhibited further decrements in all chemotactic responses, and patient-exudate neutrophils collected under Biobrane were nonmotile. The exudate neutrophils collected under Biobrane expressed high levels of Mac-1 receptors and irreversibly polymerized actin, which may contribute to the nonmotility of these exudate cells.