PERIPHERAL-BLOOD EOSINOPHILIA IN OWL MONKEYS IS ASSOCIATED WITH INCREASED EOSINOPHILOPOIESIS YET DEPRESSED RECRUITMENT KINETICS TO THE CHEMOKINE RANTES

New world nonhuman primates of the genus Aotus (owl monkeys) can be ca tegorized by 11 distinct karyotypes (K). It has been demonstrated that monkeys of K-VI persistently have one order of magnitude more eosinop hils (EOS) in the peripheral blood than K-l monkeys. The purpose of th is study was to investigate the basis for this difference and examine EOS recruitment using two cutaneous models of inflammation. Peripheral blood EOS were isolated on metrizamide gradients to greater than or e qual to 95% purity and then used for phenotypic studies. There were no significant differences when comparing karyotypes in the ratio of nor modense (K-l, 93.6% +/- 3.8%; K-VI, 78.9% +/- 8.8%) to hypodense (K-l, 6.4% +/- 3.8%; K-VI, 21.1% +/- 8.8%) EOS or their survival in culture (K-l, 5.3% +/- 2.9% at 72 hours: K-VI, 2.8% +/- 0.7% at 72 hours) (P >.05), Examination of bone narrow revealed that K-VI monkeys had great er than fivefold more EOS and EOS precursors than K-l animals. To exam ine EOS function in recruitment, monkeys of each karyotype were given a single intradermal injection of Escherichia coli lipopolysaccharide (LPS) or human recombinant RANTES. Transendothelial migration of polym orphonuclear (PMN) and mononuclear cells occurred in response to LPS a s early as 4 hours after injection; the severity of infiltration was s imilar in both karyotypes and at all time points up to 24 hours. In co ntrast, by 8 hours after intradermal injection of RANTES, leukocyte in filtration in KI monkeys consisted mostly of PMN (94.8% +/- 0.7%) that were predominantly EOS, In comparison, there was essentially no infil trate in K-VI animals at all time points, There was no difference in V CAM-1 expression in response to intradermal LPS or RANTES between the two karyotypes, These results suggest that the genetic basis of periph eral blood eosinophilia in K-VI owl monkeys is likely a function of he ightened eosinophilopoiesis and depressed recruitment kinetics from th e peripheral circulatory pool in response to RANTES. (C) 1996 by The A merican Society of Hematology.