TOTAL CELL CONTENT OF CR3 (CD11B CD18) AND LFA-1 (CD11A/CD18) IN NEONATAL NEUTROPHILS - RELATIONSHIP TO GESTATIONAL-AGE/

Neonatal neutrophils (PMN) exhibit a well-documented defect in chemota xis that is associated with several abnormalities of PMN structure and function, including deficient surface expression of CR3 (CD11b/CD18), a critical adhesion molecule, on chemoattractant-activated PMN. We re cently documented that deficient surface expression of CR3 on stimulat ed neonatal PMN is due principally to a deficiency in total cell conte nt of CR3, In the current studies, we tested the hypothesis that total cell CR3 content of PMN is even more profoundly deficient in prematur e infants and that PMN CR3 content is directly related to gestational age. A sandwich enzyme-linked immunosorbent assay for CR3 showed that PMN lysates from term neonates (greater than or equal to 37 weeks gest ation) contain about 60% of adult PMN levels of CR3, whereas PMN from premature infants (range of 27 to 36 weeks gestation) contained a mean of about 30%, ranging from 10% to 48% (P <.001 for term [n = 6] v pre mature [n = 11] by unpaired t-test). When the relationship between tot al cell CR3 and gestational age (n = 15) was analyzed, the correlation coefficient was .94 by linear regression, and the Spearman rank corre lation was significant with P <.001. PMN content of LFA-1 (CD11a/CD18) was similarly measured for 14 neonates, Term neonates were equivalent to adults in LFA-1 content of their PMN (99.4% +/- 3.2% of paired adu lt values, n = 6), whereas prematures (28 to 36 weeks gestation) were deficient, overall (69.1% +/- 10.4%, n = 8, P = .035). Below 35 weeks gestation, LFA-1 values ranged from 26% to 65% of paired adult control values, but no infant of greater than or equal to 35 weeks gestation had PMN LFA-1 content that was less than 85% of its adult control, We concluded that CR3 total cell content is more profoundly deficient in premature than in term neonates, that at birth there is a direct relat ionship between PMN CR3 content and gestational age, and that LFA-1 is deficient only in prematures less than 35 weeks of gestational age. B elow 30 weeks gestation, CR3 content of PMN approached that seen in ge netic deficiency of the CD18 family of leukocyte integrins, or type 1 leukocyte adhesion deficiency, underscoring the severity of this host impairment in very early preterm neonates. (C) 1996 by The American So ciety of Hematology.