Quantitative Determination of Secretory Immunoglobulin a (SIgA) in Middle Ear Effusions

Abstract

For the purpose of investigating the nature of middle ear effusion, quantitative analysis of secretory immunoglobulin A (SIgA) by radioactive single radial diffusion (RSRD) technique was performed on specimens of middle ear effusion and serum from the corresponding patient. Specimens consisted of 61 serous effusions (32 acute and 29 chronic type) and 29 mucoid effusions (9 acute and 20 chronic). The mean value of SIgA concentration in the serous effusions was 212.7 ± 13.5 μg/ml and that in sera from these patients was 27.0 ± 3.0 μg/ml. In the mucoid type the mean value of SIgA in effusions was 357.7 ± 13.2 μg/ml and that in sera was 24.3 ± 2.8 μg/ml. The difference in the mean value of SIgA concentration between the serous and mucoid types of effusions was statistically significant. The mean value of SIgA concentration in serous effusions was eight times that in sera from these patients and in mucoid effusions the SIgA value was approximately 14 times that in sera. The calculated percentage of SIgA in the total IgA of middle ear effusions was 11–12% in both the serous and mucoid categories. The percentage in sera was about 1%. Results of this study indicate that all middle ear effusions contain appreciable amounts of the secretory element, although the transudate from serum is the major component of effusion, and support an hypothesis that while serous middle ear effusions are a mixture of normal ear secretions bathing the membrane surface and transudates from serum, mucoid effusions are the result of enhanced epithelial secretory activity and transudates.