IgG, IgA, and IgM antibodies to mite in sera and sputa from asthmatic patients

In order to examine roles of antibodies to allergens in bronchial secretions, IgG, IgA, and IgM antibodies to mite in sputa from mite-sensitive asthmatics were measured by ELISA and compared with antibodies in sera. IgA antibodies to mite in sputa were significantly higher in mite-sensitive patients than in normal controls or mite-unsensitive asthmatic patients (P less than .01), whereas IgG and IgA antibodies in sera were significantly higher in mite-sensitive patients than in the other two groups (P less than .01). There were no significant differences of serum or sputum IgM antibodies among the three groups. The relative ratio of the level of IgA antibodies: the level of IgG antibodies was higher in sputum than in sera. IgA antibodies in bronchial secretions may play a protective role for asthma when allergens enter into the bronchial trees.