CD11b+ neutrophils predominate over RAM11+ macrophages in stretch‐injured muscle

Abstract

The purpose of this study was to determine whether both neutrophils and macrophages infiltrate the hematoma site of stretch‐injured rabbit tibialis anterior muscle. The Mab.198 antibody was used to detect CD11b⁺ neutrophils or macrophages. Neutrophils were identified specifically by using the RPN3/57 antibody. The RAM11 antibody was used to detect macrophages. The histological characteristics of the hematoma site, torn fibers or inflammatory cells, were present primarily at 4 and 24 h, but not at 48 and 72 h after injury. A difference in the Mab.198⁺ cellular concentration was detected over time between uninjured and injured muscles (P = 0.03). The injured‐uninjured difference in the RPN3/57⁺ or RAM11⁺ cellular concentrations approached significance (P = 0.07) or else was deemed insignificant (P = 0.13), respectively. Therefore, neutrophils may predominate over RAM11⁺ macrophages in stretch‐injured muscle. These findings may influence the antiinflammatory strategies used to treat stretch injuries. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 837–844, 2002