Adenoid lymphocyte responses to outer membrane protein P6 of nontypable Haemophilus influenzae in children with and without otitis media

The cellular immune responses to nontypable Haemophilus influenzae in adenoids were determined in children by measuring lymphocyte blast transformation and antibody secretion in response to the P6 outer membrane protein. In the ]ymphocyte transformation assay, stimulation index of adenoid lymphocytes stimulated by P6 in otitis children (2.34 ± 0.25) was significantly lower than that in non-otitis children (3.91 ± 0.64, p < 0.05). The number of IgM as well as IgA secreting cells after 8 days' culture with P6 were significantly smaller in otitis children (IgM: 7,534 ± 2,843/10⁶ lymphocyte; IgA: 1,573 ± 620/10⁶ lymphocyte) than those in non-otitis children (IgM: 12,994 ± 2,533, p < 0.05; IgA: 2,828 ± 528, p < 0.05). These data suggest that P6 protein is a target for the cellular immune response of the adenoid, and failure of adenoid lymphocytes to recognize it as a specific immunogen may be one of the causes of recurrent otitis media.