[Flow cytometry study on purification of human eosinophils and cell function].

The eosinophil is a well-known leukocyte acting as an effector cell in the allergic reaction mechanism. The application of appropriate materials has led to more exact results from allergic examinations. In an effort to further improve analysis, we established a novel purification method for eosinophils using the flow cytometry (PCM) of peripheral blood and bronchoalveolar lavage fluid (BALF) leucocytes from healthy and allergic subjects. We examined the function of these cells in chemotaxis by platelet activating factor (PAF) and recombinant human (rh) IL-5. We obtained following results. First, we were able to separate human eosinophils containing autofluorescence substance, which was detectable by FCM employing a 450 nm argon ion laser. Second, the purity and recovery rate of the eosinophils were 90.1 +/- 4.2% and 32.1 +/- 7.6% in the healthy subjects who had no peripheral eosinophilia (< 6%) and 93.7 +/- 4.4% and 37.2 +/- 7.5% in the allergic subjects who had eosinophila (> 6%). A relationship was readily apparent between the peripheral and purified eosinophil counts in the healthy subjects (r = 0.62). Autofluorescence of the eosinophil fraction on PCM was further found to be decreased in patients with marked eosinophilia because of an increase in hypodense eosinophils. Third, highly purified eosinophils (76%) were also obtained from the 6.5% eosinophils present in the bronchoalveolar lavage fluid of one bronchial asthma patient. Fourth, the maximal chemotaxis of these eosinophils was shown at 10(-6) M of platelet activating factor (PAF) and at 1 micrograms/ml of IL-5 in a dose-dependent manner. This activity in allergic patients was accelerated compared with that in healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)