Flow cytometric detection of histamine binding to lymphocytes

Using flow cytofluorimetry histamine binding was demonstrated by 90-100% of human peripheral blood lymphocytes. Cells were labelled with fluorescein isothiocyanate-human albumin-histamine (FITC-HA-His) and analysed using a Fluorescence Activated Cell Sorter (FACS-II). A parallel control FITC-HA conjugate and blocking with both free histamine and histamine bound to albumin were used to establish specificity. The binding of histamine could be blocked with both H1 and H2 type histamine antagonists. Nylon wool separated T and B lymphocyte subpopulations showed the same high proportions of histamine binding cells.