Am. J. Respir. Crit. Care Med.,
Volume 156, Number 5, November 1997, 1394-1398
HLA Class II Genes in Soybean Epidemic Asthma Patients
JOAN B.
SORIANO,
GUADALUPE
ERCILLA,
JORDI
SUNYER,
FRANCISCO X.
REAL,
CONXI
LÁZARO,
MARÍA J.
RODRIGO,
XAVIER
ESTIVILL,
JOSEP
ROCA,
ROBERT
RODRÍGUEZ-ROISÍN,
FERRAN
MORELL,
and
JOSEP M.
ANTÓ
Environmental and Respiratory Health Research Unit, Research Unit of Cell and Molecular Biology, Institut Municipal d'Investigació
Mèdica, Barcelona; Services of Immunology, Genetics and Pneumology, Hospital Clínic, Department of Medicine, Universitat de
Barcelona, Barcelona; and Departments of Pneumology and Biochemistry, Hospital Universitaris Vall d'Hebron, Barcelona, Spain
From 1981 to 1987, 26 outbreaks of asthma caused by the inhalation of soybean dust, affecting a total of 688 individuals, were detected in Barcelona, Spain. Because only a small proportion of asthmatic individuals living in Barcelona expressed the epidemic phenotype, it is hypothesized that a genetically determined human leukocyte antigen (HLA) Class II factor could have played a role in the
susceptible individuals. Accordingly, we studied the distribution of both HLA-DR and HLA-DQ in soybean epidemic asthmatic patients. An analysis of the HLA-DR and HLA-DQ genes for genetic polymorphisms of the
1 chain was done with the polymerase chain reaction (PCR) in 78 soybean epidemic
asthma patients, and the findings were compared with those for 67 nonepidemic asthmatic individuals and 168 individuals from the general population. An allelic disequilibrium could be established;
the risk of epidemic asthma was particularly associated with the DRB1*13 gene (p value corrected for
multiple comparisons < 0.02). The association observed for the DRB1*13 gene was stronger in individuals in the lowest tertile for total IgE, with an estimated risk with a 95% confidence interval (CI), of 14.5 (1.6 to 130.8). The combination of two genes from among the DRB1 *05-05, DRB1*05-06, and
DRB1 *06-06 genes was present in epidemic asthmatic subjects only. No association with an HLA-DQB1 allele could be observed. Genetic predisposition could contribute to the response of some
asthmatic patients to exposure to soybean dust, having led to their being affected during the epidemics of asthma in Barcelona.