Oxidation of tris and formaldehyde to CO2 by neutrophil oxidants

The buffer substance Tris is oxidized to formaldehyde by two microbicidal neutrophil oxidants, the hydroxyl radical and sodium hypochlorite. By the intact neutrophil, Tris is converted to CO2 in a process which is enhanced by stimulation with zymosan indicating that CO2 formation reflects neutrophil function. CO2 formation is more extensive at pH 6.0 than at pH 7.5 suggesting higher microbicidal activity at the low pH of inflamed tissue. In addition to Tris, its oxidation product formaldehyde is also oxidized to CO2 by hydroxyl radicals, and the formation of CO2 from formaldehyde by intact neutrophils exhibits the same features as CO2 formation from Tris. It is suggested that CO2 formation from Tris or from formaldehyde may be suitable to test for the formation of microbicidal oxidants by neutrophils.