Am. J. Respir. Cell Mol. Biol., Vol 14, No. 5, May 1996, 461-469.
PAF-induced airways hyperreactivity is modulated by mast cells in mice
M Longphre, LY Zhang, N Paquette and SR Kleeberger
Department of Environmental Health Sciences, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205.
We tested the hypothesis that mast cells contribute to platelet- activating
factor (PAF)-induced airways hyperreactivity and hyperpermeability in mice.
Airways reactivity to acetylcholine (ACh) and lung permeability to Evans
blue (EB) dye were measured before and after PAF challenge in genetically
mast cell-deficient (WBB6F1 W/Wv) and normal congenic (WBB6F1 +/+) mice, as
well as mast cell- reconstituted (BMT W/Wv) mice. In addition,
prostaglandin D2 (PGD2), a mast cell-specific mediator, was measured in the
bronchoalveolar lavage (BAL) from +/+ and W/Wv mice to determine if lung
mast cell activation was a consequence of PAF challenge. Genetically
PAF-sensitive AKR/J mice were also treated with the mast cell stabilizer
nedocromil prior to assessment of PAF effects on ACh reactivity.
Intravenous PAF (10 micrograms/kg) induced a significant (P < 0.05)
increase in airways reactivity to ACh (25 micrograms/kg) in both +/+ (371
+/- 52%) and W/Wv (122 +/- 24%) mice. There was a significantly greater
increase in +/+ compared with W/Wv mice. PAF-induced hyperreactivity to ACh
in BMT W/Wv mice (191 +/- 44%) was significantly (P < 0.05) greater than
age- matched W/Wv mice (80 +/- 16%), but not significantly different from
age-matched +/+ mice (153 +/- 44%). PAF (10 micrograms/kg) also
significantly (P < 0.5) increased lung permeability in +/+ and W/Wv
mice, but there was no significant difference between groups. BAL PGD2
increased significantly in +/+ mice following PAF challenge (559 +/- 24
ng/ml) compared with vehicle controls (152 +/- 8 pg/ml). There was no
significant increase in BAL PGD2 from W/Wv mice. Nedocromil pretreatment
significantly (P < 0.05) decreased PAF-induced hyperreactivity in AKR/J
mice but not in W/Wv mice (P > 0.05). We conclude that mast cells
contribute significantly to PAF-induced hyperreactivity but not
hyperpermeability in mice.