Differences among primates in defence against infection: Sensitivity of polymorphonuclear leukocytes to fMet‐Leu‐Phe

The sensitivity of polymorphonuclear leukocytes (PMN) to N ‐formyl‐methionyl‐leucyl‐phenylalanine (fMet‐Leu‐Phe) for chemotaxis and for lysosomal enzyme release was examined using the PMN of four primate species, human ( H. sapiens ), chipanzee ( P. troglodytes ), rhesus monkey ( M. mulatta ), and cotton‐heded tamarin ( S. (O) oedipus ). The 50 per cent effective concentration (EC 50 ) of fMet‐Leu‐Phe for chemoxaxis were 2·5 × 10 −9 M in human, 10 −9 M in chimpanzee, 8 × 10 −8 M in rhesus moneky, and 3·3 × 10 −6 M in tamarin. The EC 50 values of fMet‐Leu‐Phe for myeloperoxides (MPO) release were 10 −8 M in human, 4 × 10 −8 M in chimpanzee, 4 × 10 −8 M in rhesus monkey, and 10 −6 M in tamarin and those for β‐glucuronidase release were 4 × 10 −9 M , 6·4 × 10 −8 M , 1·8 × 10 −7 M , and 1·6 × 10 −6 M , respectively. Thus, the sensitivity of fMet‐Leu‐Phe for chemotaxis was in the order: chimpanzee ≃ human > rhesus monkey > tamarin, and that for the release of lysosomal enzymes, MPO and β‐glucuronidase, was in the order: human > chimpanzee > rhesus monkey > tamarin. These results appear to indicate that the sensitivity to fMet‐Leu‐Phe increases in the order of evolution of primates towards the human, and suggest that the sensitivity to fMet‐Leu‐Phe increases in the order of evolution of primates towards the human, and suggest that the sensitivity of PMN in the defence function against infection also increases in the same order.