OBJECTIVE AND DESIGN: This study was designed to establish the sites of formation and storage of histamine and histidine decarboxylase (HDC) in human monocytes and two of their subsets. MATERIALS AND METHODS: The experiments were carried out using monocytes from buffy coats of healthy blood donors. Histamine was quantitated by RIA, HDC activity by the formation of histamine. RESULTS: The monocyte subtype RM3/1 contained significantly more histamine than the subset 27E10 (0.041+/-0.025 vs. 0.005+/-0.004 pg/cell, p < 0.05) and also more HDC activity and HDC mRNA. After fractionation of monocyte homogenates in a discontinuous Percoll gradient or by differential centrifugation more than 80% of both, HDC activity and histamine, were recovered from the cytosolic fractions. About 50% of this histamine was found to be bound to proteins. CONCLUSIONS: In monocytes histamine and HDC are colocalized in the cytoplasm indicating a subcellular distribution different from mast cells or basophils. The data also show that histamine is synthesized by the monocytes themselves.
OBJECTIVE AND DESIGN: This study was designed to establish the sites of formation and storage of histamine and histidine decarboxylase (HDC) in human monocytes and two of their subsets. MATERIALS AND METHODS: The experiments were carried out using monocytes from buffy coats of healthy blood donors. Histamine was quantitated by RIA, HDC activity by the formation of histamine. RESULTS: The monocyte subtype RM3/1 contained significantly more histamine than the subset 27E10 (0.041+/-0.025 vs. 0.005+/-0.004 pg/cell, p < 0.05) and also more HDC activity and HDC mRNA. After fractionation of monocyte homogenates in a discontinuous Percoll gradient or by differential centrifugation more than 80% of both, HDC activity and histamine, were recovered from the cytosolic fractions. About 50% of this histamine was found to be bound to proteins. CONCLUSIONS: In monocytes histamine and HDC are colocalized in the cytoplasm indicating a subcellular distribution different from mast cells or basophils. The data also show that histamine is synthesized by the monocytes themselves.
Authors: Xiang Dong Yang; Walden Ai; Samuel Asfaha; Govind Bhagat; Richard A Friedman; Guangchun Jin; Heuijoon Park; Benjamin Shykind; Thomas G Diacovo; Andras Falus; Timothy C Wang Journal: Nat Med Date: 2010-12-19 Impact factor: 53.440
Authors: B P Ganesh; A Hall; S Ayyaswamy; J W Nelson; R Fultz; A Major; A Haag; M Esparza; M Lugo; S Venable; M Whary; J G Fox; J Versalovic Journal: Mucosal Immunol Date: 2017-07-26 Impact factor: 7.313