Evidence That Eosinophils Catalyze the Bromide-Dependent Decarboxylation of Amino Acids

Human eosinophils from subjects with or without myeloperoxidase (MPO) deficiency and guinea pig eosinophils are able to decarboxylate l-alanine in the presence of the cationic detergent cetyltrimethylammonium bromide (CTAB) but not in the presence of the nonionic detergent Triton X-100. Instead, both normal human neutrophils and guinea pig neutrophils decarboxylate l-alanine in the presence of either detergent. When the non-bromide-containing cationic detergent cetyltrimethylammonium hydroxide (CTAOH) is used instead of CTAB, the eosinophils from MPO-deficient subjects are unable to decarboxylate l-alanine. Decarboxylation occurs with the combination CTAOH-Br–, but not with the combinations CTAOH-I–, CTAOH-CI–, or CTAOH-F–. Bromide in the absence of CTAOH does not promote decarboxylation. Triton X-100 and deoxycholate are much less effective in promoting decarboxylation in the presence of bromide. l-Lysine and l-aspartic acid are decarboxylated to a considerably lower rate than l-alanine in the presence of CTAOH and Br–. It is concluded that the eosinophils can catalyze the bromide-dependent decarboxylation of the apolar amino acid l-alanine in the presence of a cationic detergent.