Reduced PMN β2 integrins after trauma: a possible role for colony-stimulating factors

SUMMARYThe β2 inlegrins are composed of a common 95-kD β-subunil (CD 18) and one of three possible α-subunils: CDlla, CDllb, or CD1le, These molecules are involved in neulrophil adhesion, diapodesis, chcmotaxis and phagocytosis. In this study, the effects of traumatic injury on neutrophil expression of these α-subunits were investigated. Neutrophils from patients with severe trauma (n = 30) were stained with fluorescent anti-CDlla, -CD1lb, or -CDlle. The percentage of positive neutrophils and the mean channel fluorescence were assayed by flow cytometry. In 10 patients and 10 normals, the effects ol'granulocyte-colony stimulating factor (G-CSF) and granulocyte-maerophage colony-stimulating factor (GM-CSF) on α–subunit expression were evaluated. Ninety-four .2% (s.e.m.) of normal neutrophils were CDlla+, 89.1% were CDllb4 and 89.8% were CDllc+. Only 65 .2% of patient neutrophils were CDlla+, 45.5% wereCDl lb+ and 8.1% were CDllc+ Culture of normal neutrophils without colony-stimulating factors resulted in reduced expression of CDlla and CDllc, but up–regulation of CDllb. Down–regulation of CDlla and CDllc was partially reversed by colony–stimulating factors (30 U/ml). CD1lb receptor density was further up-regulated by GM–CSF and G–CSF. Treatment of patient neutrophils with colony–stimulating factors in culture resulted in up–rcgulation of a–subunils as well. GM–CSF appeared to have the greater effect. These results indicate that colony–stimulating factors may have a clinical role in improving β2 integrin expression, and suggest a use in these infection–prone patients.