Potential of human polymorphonuclear leukocytes to synthesize and secrete sulfated proteoglycans

To analyze the function of proteoglycans (PG) in different types of leukocytes, both the relative amounts and specific types of proteoglycans produced by cultured human peripheral blood polymorphonuclear leukocytes (PMN) were were determined and compared to mononuclear leukocytes (PBMC). Media from 3-day cultured PMN contained significantly less (less than 10%) 35SO2-4-labeled PG than media from PBMC cultures. Incorporation of 35SO2-4 into cell-associated material was comparable for both types of white blood cells. In contrast to PBMC, PMN could not increase their synthesis or secretion of PG after exposure to concanavalin A or phorbol-12-myristate-13-acetate. Various inducers of leukocyte chemotaxis also failed to enhance PG production by PMNs. Release of prelabeled PG from PMNs could be induced by exposure to either opsonized or unopsonized zymosan (yeast) as well as the bacteria S. aureus, suggesting that particle ingestion may be accompanied by PG exocytosis. Both chondroitinase ABC and AC digested greater than 90% of PMN 35S-labeled material in media and 75% in cell lysates; HNO3 treatment removed less than 5% of N-linked 35SO4 from radiolabeled media and 25% from cells. Treatment with 0.5 N NaOH released shortened glycosaminoglycan chains from 35S-labeled PMN cell lysates. beta-D-xylosides did not stimulate an increase in polysaccharide chain production by cultured PMNs. These data suggest that PMNs can produce chondroitin 4-sulfate PG whose synthesis is not affected by treatments that alter PMN functions; in contrast to PBMCs, PMNs will actively release these molecules when exposed to micro-organisms that stimulate phagocytosis.