title: Platelet-activating factor and lyso-PAF possess direct antimicrobial properties in vitro.
abstract: The effects of platelet-activating factor (PAF) and lyso-platelet-activating factor (L-PAF) at concentrations of 0.25-20 microg/ml on potassium transport and growth of gram-positive and gram-negative bacteria have been investigated in vitro and compared with those of lysophosphatidylcholine (LPC). Potassium transport was determined using 86Rb+ as tracer, while growth was measured according to the extent of uptake of radiolabeled amino acids. All of the test phospholipids caused dose-related inhibition of 86Rb+-uptake and growth of gram-positive bacteria, the order of potency being PAF>LPC>L-PAF. Gram-negative bacteria, on the other hand, were less sensitive to the inhibitory effects of the phospholipids on K+ transport and growth. Some, but not all, of the gram-positive and gram-negative bacteria were able to degrade LPC, but not PAF or L-PAF, demonstrating that enzymatic degradation of phospholipids does not explain the differential sensitivity to these agents. The bioactive phospholipids LPC, PAF and L-PAF may represent an oxygen-independent antimicrobial host defense system operative primarily against gram-positive bacteria.
authors.affiliation: Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, Institute for Pathology, University of Pretoria, Republic of South Africa. hsteel@postillion.up.ac.za
authors.forename: H C
authors.initials: HC
authors.lastname: Steel
authors.forename: R
authors.initials: R
authors.lastname: Cockeran
authors.forename: R
authors.initials: R
authors.lastname: Anderson
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D018836:Inflammation Mediators / Q000494:pharmacology*; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D018836:Inflammation Mediators; D008244:Lysophosphatidylcholines; C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D012413:Rubidium; D011188:Potassium