Decreased expression of the common acute lymphoblastic leukaemia antigen (CALLA/CD10) on neutrophils from patients with thermal injury

The common acute lymphoblastic leukaemia antigen (CALLA/CD10) is a normal component of the circulating neutrophil cell surface membrane. In order to examine the potential functional significance of CALLA/CD10 we analysed the expression of this molecule on neutrophils isolated from thermal injury patients, since these patients have a well-documented constellation of neutrophil defects affecting their microbicidal functions. Expression of neutrophil CALLA/CD10 was monitored by indirect immunofluorescence and flow cytometry. We observed that CALLA/CD10 expression was quantitatively reduced on burn patient neutrophils, compared to healthy donors (P < 0.001). In contrast, burn patient neutrophils expressed normal levels of class I HLA molecules and the C3bi receptor. Reduced expression of CALLA/CD10 was not associated with neutrophil activation or exposure to plasma 'factor(s)' in vivo. Analysis of normal bone marrow neutrophils by cell sorting indicated that expression of CALLA/CD10 occurs late in neutrophil maturation, since 25% of polymorphonucleated bone marrow neutrophils did not express cell surface CALLA/CD10. Attempts to examine the chemotactic responses of CALLA/CD10 positive and negative neutrophils from burn patients were hampered by previous exposure of these cells to chemoattractants in vivo. Collectively, our findings suggest that burn patient peripheral blood neutrophils may be deficient in CALLA/CD10 due to insufficient maturation time in the bone marrow following thermal injury.