Serum-associated inhibition of neutrophil Fc receptors in cancer patients

Rosettes with ox erythrocytes coated with purified IgG antibody were used to detect Fc receptors on neutrophils from 60 patients with solid neoplasias and from 55 normal controls. The mean average of the rosettes in the patients was 48.10%, and that in normal controls was 79.42%, with a highly significant difference according to the Wilcoxon test [negative probability, P(W) = 4.47·10^-5]. The low proportion of patients' rosettes was related to the presence of a serum factor, which also inhibited normal neutrophil rosettes formation. Patient neutrophils (or normal neutrophils treated with patient sera) recovered their rosetting capacity when cultured in vitro. No correlation was found between low percentages of rosette-forming cells and the level of circulating immune complexes of the individual patients. Additional evidence also supported the finding that IC and the serum factor are probably unrelated.