Characterization of novel stem cell factor responsive human mast cell lines LAD 1 and 2 established from a patient with mast cell sarcoma/leukemia;: activation following aggregation of FcεRI or FcγRI

Two novel stein cell factor (SCF) dependent human mast cell lines, designated LAD I and 2, were established from bone marrow aspirates from a patient with mast cell sarcoma/leukemia. LAD1 and 2 cells have the ultrastructural features of human mast cells, and express FcepsilonRI, CD4, 9, 13, 14, 22, 31, 32, 45, 64, 71, 103, 117, 132, CXCR4 (CD 184), CCR5 (CD 195); and intracytoplasmic histamine, tryptase and chymase. LAD I and 2 do not exhibit activating mutations at codon 816 of c-kit. Both LAD I and 2 release beta-hexosaminidase following FcepsilonRI or FcgammaRI aggregation. The availability of these cell lines offers an unparalleled circumstance to examine the biology of human mast cells.