Role of mast cells in the onset of IgE-mediated late-phase cutaneous response in mice.
BACKGROUND
In mice that are passively sensitized to IgE, cutaneous antigen challenge produces a biphasic response with peaks at 1 and 24 hours after challenge.


OBJECTIVE
We investigated the role of mast cells in the IgE-mediated late-phase reaction in mice.


METHODS
We histologically and ultrastructurally investigated the morphologic changes of mast cells during the biphasic responses.


RESULTS
Degranulation of mast cells, which was observed between 4 and 24 hours after challenge, reached a peak at 8 hours. Piecemeal degranulation was seen during the immediate phase reaction. The number of IL-6-positive mast cells was increased after 4 hours in both IgE-sensitized and unsensitized mice, but positive cells showed a greater increase in sensitized mice and reached a peak after 8 hours. With in situ hybridization experiments, mast cells were positive for IL-6 messenger RNA at 6 hours after challenge.


CONCLUSIONS
These findings indicate that anaphylactic degranulation of mast cells and the expression of IL-6 mRNA within 4 hours after antigen challenge are important for the onset of the late-phase allergic cutaneous reaction in mice.
Nagai
H
H
Department of Pharmacology, Gifu Pharmaceutical University, Japan.
Abe
T
T
Yamaguchi
I
I
Mito
K
K
Tsunematsu
M
M
Kimata
M
M
Inagaki
N
N
D000818:Animals; D003876:Dermatitis, Atopic / Q000209:etiology*; D005260:Female; D006968:Hypersensitivity, Delayed / Q000209:etiology*; D007073:Immunoglobulin E / Q000494:pharmacology*; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D008407:Mast Cells / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D012333:RNA, Messenger / Q000378:metabolism
D015850:Interleukin-6; D012333:RNA, Messenger; D007073:Immunoglobulin E