sq-23377 and lipoteichoic-acid

CD36 has recently been shown to facilitate monocyte Toll-like receptor 2 (TLR2) recognition of lipoteichoic acid (LTA), much like CD14 in TLR4 recognition of lipopolysaccharide. We previously found that bovine gammadelta T cells express CD36 transcripts. Here, we tested whether bovine gammadelta T cells express CD36 protein and if so, whether it functions in a manner similar to the monocyte molecule. CD36 transcripts and internal and cell surface protein could be detected in resting, sorted gammadelta T cells. Phorbol 12-myristate 13-acetate (PMA)/ionomycin treatment increased CD36 transcript levels (detectable at 4 h) and protein expression (internal and cell surface). Increased surface antigen expression was detectable by 24 h and was maximal at 72 h following PMA/ionomycin stimulation. Anti-CD36 monoclonal antibody inhibited increased macrophage-inflammatory protein-1alpha gene expression in gammadelta T cells activated by LTA. In conclusion, gammadelta T cells express CD36, previously thought to be a myeloid and endothelial cell-restricted surface antigen, and it contributes to responses by these cells to microbial LTA.

Topics: Animals; Antibodies, Monoclonal; Cattle; CD36 Antigens; Immunoglobulin M; Ionomycin; Lipopeptides; Lipopolysaccharides; Peptides; Receptors, Antigen, T-Cell, gamma-delta; T-Lymphocyte Subsets; Teichoic Acids; Tetradecanoylphorbol Acetate; Toll-Like Receptor 2

Lipoteichoic acid (LTA) from Streptococcus faecalis stimulates the respiratory burst in peripheral blood monocytes (mon), as measured by cytochrome C reduction. The effect of LTA was time and dose dependent. LTA stimulated the respiratory burst in a biphasic manner within a range of 1 to 1000 ng/ml.10(6) mon, with maximal activity at 50 ng/ml. At this concentration LTA increased the activity from 0.97 +/- 0.2 to 4.88 +/- 0.2 nmol.10(6) mon/20 min. The role of calcium ions in the effect of LTA in stimulating respiratory burst was studied by changing the availability of calcium ions in the medium, and by measuring the effect of LTA on 45Ca2+ uptake and on intracellular Ca2+ levels. Removal of extracellular calcium ions in the presence of the calcium chelator EGTA, abolished the LTA-stimulated respiratory burst. LTA (50 ng/ml) was found to increase 45Ca2+ uptake into monocytes within seconds (from 2200 +/- 242 in the untreated cells to 4642 +/- 365 cpm/min in the LTA-treated mon). At this concentration, LTA stimulated an immediate rise in the intracellular free Ca2+ concentration to 155 +/- 15 nM as compared with 120 +/- 14 nM in the unstimulated monocytes. LTA caused a specific release of arachidonic acid indicating the involvement of phospholipase A2 in the transduction signal stimulating the respiratory burst by LTA.

Topics: Antigens, Bacterial; Calcium; Cytochrome c Group; Egtazic Acid; Enterococcus faecalis; Humans; In Vitro Techniques; Indomethacin; Ionomycin; Lipopolysaccharides; Monocytes; Oxygen Consumption; Phospholipases; Phospholipases A; Phospholipases A2; Quinacrine; Signal Transduction; Teichoic Acids; Tetradecanoylphorbol Acetate; Zymosan