Otitis media in the young infant: an IgE-mediated disease?

IgE antibody directed against noncapsular antigens of mechanically disrupted Streptococcus pneumoniae, serotype 3 rough, was demonstrated in middle ear effusions (MEE) and serum of infants with and without prior evidence of pneumococcal otitis media with effusion (OME). The techniques employed included radioimmunoassay (RIA), passive skin testing, Prausnitz-Küstner (P/K), and enzyme-linked immunospecific assay (ELISA). Adsorption of MEE with ultrasonically disrupted crude pneumococcal antigen (CPA-U) resulted in a reduction of total IgE counts per minute and suggested bacteria-specific IgE antibody ranging from approximately 22 to 92% of the total IgE. The biological activity of the IgE antibody was confirmed by challenging skin passively sensitized with MEE IgE and CPA-U. Areas of induration appeared 20 minutes after challenge and continued to increase in size until 90 minutes. An ELISA procedure was developed as a tool to determine the nature of the antigen(s) and to determine the class(es) of antibody other than IgE. It appeared that CPA-U possesses free amino groups and that it can withstand the rigors of autoclaving. An analysis of 45 cord bloods revealed that high levels of IgG CPA-U antibody occur in this type of sample and that no correlation exists between the IgE and IgG levels. The mean IgG:IgE ratio, optical density at 420 nm (OD 420), for cord bloods was 2.49. In contrast, serum samples from nine infants without pneumococcal otitis media and from 14 infants with pneumococcal otitis media had lower levels of IgG antibody. There was no significant relationship between IgG and IgE OD 420 in infants who never had an episode of pneumococcal otitis media and the mean IgG:IgE was 1.88, whereas the ratio for those infants with pneumococcal otitis media was 1.56. In addition, there was a significant correlation between IgG and IgE levels in this latter group. The results suggest that it may be important to monitor the levels of at least these two classes of antibody to enhance our understanding of the pathogenesis and recovery from otitis media.