Chemotactic receptor of cord blood granulocytes to the synthesized chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine.

Chemotactic mobility of cord blood granulocytes (CBG) was studied under varying concentrations of synthesized chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (f . Met-Leu-Phe). The maximal chemotactic mobility was found at a concentration of 2 X 10(-7)M in CBG and 1 X 10(-7)M in adult blood granulocytes (ABG) (n = 8). The maximal distance of granulocyte mobility of CBG was significantly shorter than that of ABG (P less than 0.01). The number of chemotactic receptors and the affinity constant were assayed by the competitive inhibition method, using f . Met-Leu-[3H]Phe, and the data were subjected to Scatchard analysis. The number of chemotactic receptors of ABG was 2.5-fold of CBG, as shown by 21,800 +/- 7800 per cell in ABG (n = 3) and 9000 in CBG (n = 1). This figure was confirmed by the one point assay method by increasing the sample numbers of cord blood. It was found that bound chemotactic peptide (X 10(-14) moles/10(7) cells) was 7.9 +/- 0.7 in ABG (n = 4) and 3.4 +/- 0.7 in CBG (n = 5). Affinity constants were similar in CBG and ABG.