Differential Sensitivities of Purified Human Eosinophils and Neutrophils to Defined Chemotaxins

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Abstract
Functions of eosinophils and neutrophilis isolated from normal human blood were determined by measuring chemotactic migration and release of .beta.-glucuronidase. Four well-characterized chemotaxins, the complement fragment C5a, formyl-methionyl-leucyl-phenylalanine (FMLP), platelet-activating factor (PAF), and leukotriene B4 (LTB4) were used as stimuli. Neutrophils showed remarkable chemotatic responses to all four chemotaxins. In contrast, eosinophils showed a significant chemotatic response to C5a and PAF, but only weak responses to FMLP and LTB4. Using these chemotaxins we found the following order of chemotatic potency (maximal number of migrated cells): C5a = LTB4 > FMLP >PAF for neutrophilis and PAF = C5a > LTB4 = FMLP for eosinophils. Neutrophils elicited a significant .beta.-glucuronidase release when stimulated by C5a and FMLP, whereas only small amounts were released with PAF and LTB4. On the other hand, an amount of .beta.-glucuronidase released from eosinophils comparable to that from neutrophils was elicited only with C5a. FMLP, LTB4, and PAF caused the release of small percentages of .beta.-glucuronidase. The important cellular functions of eosinophils and neutrophils, chemotaxis and enzyme release, are thought to be controlled by differential responsiveness to stimuli.