The production of macrophage inflammatory protein-1 alpha by human basophils

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) has previously been shown to be produced by mononuclear cells, eosinophils, and neutrophils. Its production by basophils has not been investigated. The objective of this study was to investigate the production of MIP-1 alpha by basophils. Peripheral blood basophils were separated by Percoll gradient centrifugation, cultured overnight, and processed for double immunocytochemistry using Abs against MIP-1 alpha and Fc epsilon RI alpha (alpha subunit of IgE receptor type I). We demonstrated that basophils expressed immunoreactive MIP-1 alpha upon stimulation with anti-IgE. Less than 5% of the basophils stained for MIP-1 alpha without stimulation. The secretion of MIP-1 alpha by basophils was studied by ELISA. In these experiments, basophils were further enriched to 65 to 99% (median, 86%) by a negative selection method. Basophils released MIP-1 alpha when stimulated by Abs against IgE and Fc epsilon RI alpha as well as IL-3 and the calcium ionophore, A23187. In parallel experiments, PBMC, eosinophils, and neutrophils did not produce MIP-1 alpha in response to anti-IgE, but they did so in response to A23187. No MIP-1 alpha release was detected in platelet preparations. Preincubation with IL-3 (15 min or 18 h) augmented anti-IgE-induced basophil MIP-1 alpha production. The secretion of MIP-1 alpha by basophils was detectable shortly after stimulation and gradually increased over 24 h. Since MIP-1 alpha has potent inflammatory and histamine releasing activities, its production by basophils may indicate a positive feedback mechanism for allergic inflammation.