The Production of Macrophage Inflammatory Protein-1α by Human Basophils

Macrophage inflammatory protein-1α (MIP-1α) 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-1α by basophils. Peripheral blood basophils were separated by Percoll gradient centrifugation, cultured overnight, and processed for double immunocytochemistry using Abs against MIP-1 a and Fc∈R1α (α subunit of IgE receptor type I). We demonstrated that basophils expressed immunoreactive MIP-1α upon stimulation with anti-IgE. Less than 5% of the basophils stained for MIP-1α without stimulation. The secretion of MIP-1α 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-1α when stimulated by Abs against IgE and Fc∈R1α as well as IL-3 and the calcium ionophore, A23187. In parallel experiments, PBMC, eosinophils, and neutrophils did not produce MIP-1α in response to anti-IgE, but they did so in response to A23187. No MIP-1α release was detected in platelet preparations. Preincubation with IL-3 (15 min or 18 h) augmented anti-IgE-induced basophil MIP-1α production. The secretion of MIP-1α by basophils was detectable shortly after stimulation and gradually increased over 24 h. Since MIP-1α has potent inflammatory and histamine-releasing activities, its production by basophils may indicate a positive feedback mechanism for allergic inflammation.