Fibroblasts determine the fate of Fc epsilon RI+ cell populations in vitro by selectively supporting the viability of mast cells while internalizing and degrading basophils.
To determine the fate of Fc epsilon RI+ cells on fibroblasts in vitro, human bone marrow derived CD34+ cells were cultured in the presence of recombinant human interleukin 3 and recombinant human hematopoietic stem cell factor for 3 weeks, and Fc epsilon RI+ cells were purified by immunomagnetic selection. This enriched Fc epsilon RI+ cell population consisted of 92-94% basophils and 3-5% mast cells as determined by morphologic, immunohistochemical, and ultrastructural criteria. The Fc epsilon RI+ cells were then cocultured with 3T3 fibroblasts. Basophils decreased markedly by 1 week and were absent from cocultures by 2-3 weeks, while the mast cell numbers on the fibroblast monolayers remained constant. Ultrastructural examination of cocultures at 2 days demonstrated phagocytosis of basophils by fibroblasts. By 1 week, phagocytosed basophil membranes and granules gave fibroblasts the superficial appearance of mast cells by toluidine blue staining. Mast cells surviving in cocultures could be distinguished from granule-containing fibroblasts by IgE surface labeling and by ultrastructural demonstration of tryptase-positive granules. Thus, while mast cells remain viable in coculture with 3T3 fibroblasts, basophils do not survive and are internalized and degraded by the fibroblast monolayer.
Kirshenbaum
A S
AS
Allergic Diseases Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md 20892.
Goff
J P
JP
Albert
J P
JP
Kessler
S W
SW
Metcalfe
D D
DD
D001491:Basophils / Q000502:physiology* / Q000648:ultrastructure; D002452:Cell Count; D002478:Cells, Cultured; D053818:Chymases; D005347:Fibroblasts / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D008407:Mast Cells / Q000502:physiology* / Q000648:ultrastructure; D010587:Phagocytosis; D017455:Receptors, IgE / Q000502:physiology*; D012697:Serine Endopeptidases / Q000032:analysis; D053802:Tryptases
D017455:Receptors, IgE; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases