POLYMORPHONUCLEAR CELLS IN CHRONIC-HEMODIALYSIS PATIENTS HAVE INTACT PHAGOCYTOTIC AND IMPAIRED BACTERICIDAL ACTIVITIES

Although it has been well documented that chronic hemodialysis (HD) pa tients are highly susceptible to infectious diseases, the reasons for this have yet to be clarified. The present study was thus designed in order to better define this issue. Fifty-eight stable chronic HD patie nts without any evidence of infection were selected for the study. Blo od samples were collected before and after HD from the same patient to determine the effect of HD. Reactive oxygen species (ROS) production in polymorphonuclear cells (PMNC) was measured by chemiluminescence us ing luminol. When the PMNC collected after HD were stimulated in vitro with a calcium ionophore (A23187), they produced a larger amount of R OS than that obtained from healthy volunteers [mean 7.4 x 10(5) photon counts (n = 58) vs. 3.0 x 10(5) photon counts (n = 17), p < 0.01]. A higher production of ROS after HD was seen in patients using membranes such as cellulose triacetate, polymethylmetacrylate and cellulose dia cetate, whereas cuprophane did not seem to augment ROS production at a ll. On the other hand, when the PMNC after HD were stimulated with pho rbol myristate acetate, their photon counts (mean 4.3 x 10(7)) were co mparable to those before HD (mean 3.5 x 10(7)), and to those of PBMC o btained from healthy volunteers (mean 4.1 x 10(7)). It was thus sugges ted that the enhanced ROS production of PMNC was related to some stimu li, possibly even to the assay used to measure ROS. The phagocytotic a ctivity and bactericidal effect of PBMC were measured by coculturing 1 x 10(5) PMNC with 1 x 10(5) CFU of Escherichia coli. Similar phagocyt otic activities were noted in the PMNC from healthy volunteers and chr onic HD patients before and after HD: the mean number of phagocytosed bacteria (log(10) CFU) was 3.3, 3.3, and 3.3, respectively. However, i n the case of a bactericidal effect, only the PMNC from healthy volunt eers, but not the PMNC from HD patients, could effectively kill the ba cteria, since the number of bacteria in PMNC decreased from 10(3.3) to 10(2.1). The PMNC from HD patients could not kill the bacteria regard less of the characteristics of the membranes. It was thus concluded th at the PMNC of chronic HD patients possess an intact phagocytotic acti vity which impaired bacterial killing, and was probably due to an abno rmality occurring in the ROS production pathway.