Passive sensitization of human airways induces mast cell degranulation and release of tryptase.
BACKGROUND
This study was designed to examine the effect of passive sensitization (PS) on human bronchial mast cells. PS with asthmatic serum induces a hyper-responsiveness to nonspecific agonists, and immunoglobulin (Ig)E binding mainly on mast cells.


METHODS
Bronchi dissected out from 19 lung specimens were incubated in normal or asthmatic serum. Immunohistochemistry was performed using monoclonal antibodies (MoAbs) directed against tryptase, chymase, or c-kit. Mast cells were classified as fully granulated (type I), partly (type II) or largely degranulated (type III). Tryptase was measured in supernatant using ELISA. Contractile response was recorded in a separated set of experiments using an organ bath system.


RESULTS
PS decreased both tryptase positive cells (47.9 +/- 10.0 vs. 26.7 +/- 4.8 cell/mm2, P = 0.003) and chymase positive cells (26.1 +/- 3.3 vs. 14.9 +/- 1.8 cell/mm2, P = 0.01), but did not alter the number of c-kit positive cell. PS decreased the proportion of type I (55.4 vs. 28.9%, P < 0.0001) and, concomitantly increased that of types II (23.2 vs. 41.0%, P < 0.0001) and III (21.4 vs. 30.1%, P = 0.04). Following PS, tryptase concentration significantly increased and the magnitude of histamine response, was correlated with the amount of type II mast cells.


CONCLUSIONS
PS of human isolated bronchi induces a mast cell degranulation related to in vitro hyper-responsiveness, along with a tryptase release.
Berger
P
P
Laboratoire de Physiologie Cellulaire Respiratoire, Université Victor Ségalen Bordeaux 2, France.
N'guyen
C
C
Buckley
M
M
Scotto-Gomez
E
E
Marthan
R
R
Tunon-de-Lara
J M
JM
D001249:Asthma / Q000276:immunology*; D001980:Bronchi / Q000276:immunology*; D016535:Bronchial Hyperreactivity / Q000276:immunology; D015550:Cell Degranulation; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology; D007106:Immune Sera / Q000276:immunology*; D007116:Immunization, Passive; D008297:Male; D008407:Mast Cells / Q000276:immunology*; D012697:Serine Endopeptidases / Q000378:metabolism*; D053802:Tryptases
D007106:Immune Sera; D012697:Serine Endopeptidases; D053802:Tryptases