Human mast cell line-1 (HMC-1) cells exhibit a membrane capacitance increase when dialysed with high free-Ca2+ and GTPγS containing intracellular solution

An increase in cytosolic free calcium concentration [Ca2+]; initiates the exocytotic activity in various types of secretory cells. The guanosine 5 '-0-[3-thio]triphosphate (GTP gamma S), a non-hydrolysable analogue of GTP (guanosine 5'-triphosphate), is an effective secretagogue for different cell types of different species, like mast cells, neutrophils or eosinophils. Consequently, the internal administration of GTP gamma S causes degranulation of mouse and rat mast cells. Regarding rat mast cells, it is proved that Ca2+ can cooperate with GTP or GTP gamma S in accelerating and increasing amplitude of the secretory response. All the previous studies with respect to capacitance recordings and mast cells were performed using mouse or rat mast cells, usually derived from peritoneum or the Ear basophilic leukaemia cell line RBL. In this study, we applied the capacirance measurement technique to the human mast cell line-1 (HMC-1) cells, an immature cell line established from a patient with mast cell leukaemia. Parch clamp dialysis experiments revealed that high intracellular free Ca2+ and GTP gamma S concentrations are both required for considerable capacitance increases in HMC-1 cells. During degranulation of HMC-1 cells, the total membrane capacitance (C-m) increase appeared continuously and, in some cases, as a discrete capacirance change, developing in a stepwise manner. Then, we tested the effect of latrunculin B upon HMC-1 cell capacitance increase as well as of some classic mast cell stimulators like PMA, A23187 and IL-1 beta in hexosaminidase release. Finally, we could conclude that the HMC-1 cell line represents a suitable model for the study of human mast cell degranulation. (C) 2013 Elsevier B.V. All rights reserved