Heterogeneity of Fc receptor expression in chemotaxis and adherence of neonatal neutrophils.

Chemotaxis and adherence to polymorphonuclear neutrophils (PMN) subpopulations from cord blood of 13 healthy neonates and blood of 16 healthy adults as control subjects were determined using the rosette-forming procedure, the modified Boyden method, and 51Cr adherence assay. The percentage of rosette-forming neutrophils (RFN) (Fc receptor expression) of cord PMN (35 +/- 8%) was significantly lower than that of adult PMN (60 +/- 4%, p less than 0.01). Differences in chemotaxis of PMN subpopulations between cord and adult PMN after stimulation by their own endotoxin-activated plasma were as follows: (i) unfractionated adult PMN (A) (n = 10) versus adult RFN (B) (n = 5) versus adult nonRFN (C) (n = 5); (A) less than (B), p less than 0.01 and (A) greater than (C), p less than 0.01; (ii) unfractionated cord PMN (a) (n = 5) versus cord RFN (b) (n = 5) versus cord non-RFN (c) (n = 5); (a) less than (b), p less than 0.01 and (a) versus (c), NS; (iii) (A) greater than (a), p less than 0.01; (iv) (B) greater than (b), p less than 0.05 and (C) versus (c), NS. Similarly, differences in adherence were as follows: (i) (A) (n = 13) versus (B) (n = 4), NS and (A) greater than (C) (n = 4), p less than 0.01; (ii) (a) (n = 4) versus (b) (n = 4), NS and (a) greater than (c) (n = 4), p less than 0.01; (iii) (A) greater than (a), p less than 0.05; (iv) (B) versus (b), NS and (C) versus (c), NS. These results suggest that differences in chemotaxis and adherence between cord and adult PMN may relate in part to differences of PMN subpopulations.