The Selective Polymorphonuclear Neutrophils (PMN) Degranulation as the Probable Additional Mechanism of the Hemodialysis (HD)-induced Complement Activation

The intracellular lysozyme and beta-glucuronidase contents were estimated in PMN isolated from peripheral blood before HD and those from the first portion of full blood leaving the dialyser. The lysozyme estimations were done by the use of the turbidimetric method and beta-glucouronidase was assayed by measuring the release of phenolphtalein from its beta-glucuronate. The cells leaving the cellophane dialyser showed the significantly decreased lysozyme contents while the estimated intracellular activity of beta-glucuronidase was practically equal in both evaluated samples. The results seem to indicate that the HD-associated complement activation may result not only from the simple plasma-cellophane ineteraction. The direct cleavage of the inactive C5 complement component by products released from the PMN specific granules seems to play an important role too. For several years it has been known that the hemodialysis (HD)-induced granulopenia is the result of the pulmonary polymorphonuclear neutrophils (PMN) sequestration (Toren et al., 1970). Recent studies have established that this phenomenon is the consequence of complement activation leading to PMN aggregation with subsequent pulmonary vascular embolization and/or PMN adherence to endothelial surface (Craddock et al. 1977a, Craddock et al., 1979). It was also observed that the contact of patients plasma or plasma obtained from experimental animals with dialyser cellophane results, both in vitro and during HD, in the appearance of the activities: inducing the PMN aggregation, chemotactic and augmenting the PMN adherence (Craddock et al. 1977b, Wysocki et al. 1980). At least the two first are identified as related to the presence of the C5a complement component (Craddock et al., 1977b, O'Flaherty et al., 1979). Similarly, the disseminated complement activation appears to be the main reason of granulopenia accompanying the filtration leukapheresis (FL), the procedure suitable for PMN collection from donors peripheral blood (Hammerschmidt et al., 1978). The PMN are there sequestered in nylon wool layer and subsequently eluted for transfusion purposes. The exposition of blood to artificial surface leads there, like during HD, to the complement (C5) activation. Although, as reported by Wright et al.) 1978b), when plasma and leukocyte enriched blood were diverted by a cell separator before passage through nylon wool filters during FL, complement activation was evident only in plasma from blood containing leukocytes, indicating that extracorporeal complement activation during FL is dependent in large part upon the interaction of leukocytes with nylon wool. The more precise studies of these authors (Wright et al., 1978a) may imply, that the PMN granule constituents released after the previous adherence of cells to nylon fibers are responsible for the FL-associated complement activation. The following studies were done in order to evaluate if the PMN degranulation may take part also in complement activation during hemodialysis carried out with the use of cellophane equipment.