Lectin-Mediated, Nonopsonic Phagocytosis of Type 1 Escherichia coli by Human Peritoneal Macrophages of Uremic Patients Treated by Peritoneal Dialysis

Abstract

Human peritoneal macrophages isolated from uremic patients undergoing peritoneal dialysis bind type 1 fimbriated Escherichia coli in the absence of opsonins. The number of bacteria bound per macrophage was 6.9, as determined by microscopic examination. Methyl alpha-mannoside (0.1 mM) and p-nitrophenyl alpha-mannoside (0.01 mM) inhibited this binding by about 66%. The ability of peritoneal macrophages to bind E. coli in a mannose-specific manner was confirmed in further experiments using an enzyme-linked immunosorbent assay (ELISA) with an antibacterial antibody, radiolabelled E. coli, and counts of colony-forming units (CFU). The number of bacteria bound per macrophage was 7 to 12 in the ELISA and 5.5-8.5 in the CFU assay. Methyl alpha-mannoside caused 70% inhibition of binding in the ELISA and 84% in the CFU assay, whereas p-nitrophenyl alpha-mannoside showed inhibition of 79% and 90%, respectively. Most bound bacteria (76-80%) were subsequently killed. Nonfimbriated E. coli 827 bound poorly to the macrophages (approximately 22%) as compared to that of the fimbriated bacteria. Although this binding was not inhibited by methyl alpha-D-mannoside or p-nitrophenyl alpha-mannoside, the percentage of bacteria killed was similar to that of the fimbriated phenotype. The peritoneal macrophage is thus able to phagocytose E. coli in the absence of opsonins. This may explain the relative rarity of E. coli as an etiologic agent of peritoneal infections in the dialysed patient.

Host and Bacterial Factors Involved in the Innate Ability of Mouse Macrophages To Eliminate Internalized UnopsonizedEscherichia coli

“…The assay conditions, the criteria used to assess killing, and the magnitude of the differences shown in this earlier report leave open the possibility that there may be little difference between the killing of FimH ϩ and FimH Ϫ E. coli once internalization has occurred. Consequently, our results support observations that piliation has little effect on the outcome of nonopsonic phagocytosis as far as killing of ingested bacteria is concerned (5,6,16,22 (3,14,24,52), it may be that certain macrophage populations vary in the expression of receptor type as well as density.…”

Bacteremia Complicating Peritonitis in Peritoneal Dialysis Patients

“…amongst the gram-negative organisms [9], E. coli has rarely been reported to cause peritonitis in peritoneal dialysis patients, and we have previously suggested that this may be due to the ability of the peritoneal macrophage to phagocytose E. coli even in the absence of opsonins [10],…”

Glycobiological aspects of the activation of phagocytes respiratory chain

“…Пили представ ляют собой лектины на поверхности бактериальных клеток, специфич ные к остаткам маннозы (пили 1-го типа), галактозы (пили 2-го типа) или других углеводов. Соответствующие взаимодействия лежат в ос нове явления «лектинофагоцитоза», обеспечивающего инактивацию па тогенных микроорганизмов фагоцитами [45]. Показано, что связыва ние бактериальных клеток Е. coll, несущих пили 1-го типа, с нейтро филами человека сопровождается развитием хемилюминисцентного от вета клеток [40] и образованием Н 2 0 2 в реакции с гомованилиновой кислотой [42], которые блокировались а-метил-Э-маннозидом.…”