Granulocyte response to oxidized FMLP. Evidence for partial inactivation of FMLP

Measurement of environmental formylmethionyl-peptides

Formylmethionyl-peptides are naturally occurring, biologically active ligands produced by bacteria. They produce a variety of biological effects including neutrophil chemotaxis, cellular degranulation, oxygen-free radical production, and smooth muscle contraction. Our studies have demonstrated that oxidized and reduced forms of formylmethionyl-leucyl-phenylalanine (fMLP) can be detected in bulk environmental organic dust samples. Organic dust fMLP content may not reflect total formylmethionyl-peptide content and pathological sequelae. Attempts to develop a total formylmethionyl-peptide assay that would reflect its pathological potential have thus far been unsuccessful. Information has been derived concerning the biology of formylmethionyl-peptides from these studies. Chromatographic, radioenzymatic, and radioreceptor-ligand binding studies were performed. High-performance liquid chromatography (HPLC) analysis of synthetic and environmental fMLP demonstrated that fMLP is labile, forming three oxidation products. HPLC is limited by inadequate sensitivity for air sample analysis and the probability of the presence of multiple formylmethionyl-peptides. Deformylases were isolated from Escherichia coli, but their usefulness in a competitive assay to detect formylmethionyl-peptides was limited by specificity differences from that for biological receptors. Receptor binding studies were conducted in an attempt to replace the deformylase with a biological receptor. The receptor binding patterns noted were consistent with the existence of three distinct formylmethionyl-peptide receptor subsets in neutrophils and alveolar macrophages. The plurality of fMLP receptor subtypes interfered with formylmethionyl-peptide measurement in a competitive assay. Formylmethionyl-peptides may contribute to organic dust-induced disease, but better techniques for the assessment of exposure to these agents are needed to properly assess their health impact.

Chemiluminescence and chemotaxis assay of canine granulocytes: a methodological study

Chemiluminescence (CL) of isolated granulocytes and of whole blood from dogs was evaluated. Chemiluminescence of whole blood samples created an undesired quenching effect by the red blood cells which makes the assay difficult to apply in pathological cases with low formation of oxygen metabolites. This problem was avoided when chemiluminescence was determined, using isolated granulocytes. A cell concentration of 5 x 10(9)/l was needed to create optimal conditions. The Boyden chamber technique was used for study of random migration and chemotaxis. Casein (0.1%), zymosan activated serum with and without epsilon-amino-n-caproic-acid and homologous serum were effective chemoattractants for canine granulocytes, while FMLP (formyl-methionyl-leucyl-phenylalanin) did not attract canine granulocytes.

Extracts of feverfew inhibit mitogen-induced human peripheral blood mononuclear cell proliferation and cytokine mediated responses: a cytotoxic effect

Feverfew has been used since antiquity to treat inflammatory conditions. Extracts of the herb were found to inhibit mitogen-induced tritiated thymidine ([3H]-TdR) uptake by human peripheral blood mononuclear cells (PBMC), interleukin 2 (IL-2)-induced [3H]-TdR uptake by lymphoblasts and PGE2 release by interleukin 1 (IL-1)-stimulated synovial cells. Parthenolide, a major secondary metabolite from the herb also blocked [3H]-TdR uptake by mitogen-induced PBMC. However, both crude extracts and parthenolide proved cytotoxic to mitogen-induced PBMC and IL-1 stimulated synovial cells, the cytotoxic effect being functionally indistinguishable from the inhibitory effects. The pharmacological properties of feverfew may thus be due to cytotoxicity, although the time course of the events described in this paper is different from those where feverfew appears to have more specific inhibitory effects.