Respiratory burst activity and nitric oxide production. Respiratory burst activity of HK leucocytes was based on the reduction of ferricytochrome c method for the detection of extracelular o production as described by Secombes . Optical densities(OD) were converted to nmol of O produced by multi- plying by 15.87 as described by Pick. Nitric oxide(NO) production by HK leucocytes was assessed as described by Neumann et al. using the Griess reaction to quantify nitrite content of the leucocytes supernatant, against a standard curve produced with known concentrations of sodium nitrite. To stimulate No production the adherent leucocytes monolayer was incubated for 72 h, at 18 C, with L15 medium containing 5%FBS and LPS(Lipopolysaccharide from Escherichia coli serotype 0111B4. Sigma; 1 uM)in triplicate