Alteration of adenoid tissue alkaline and acid phosphatase in children with secretory otitis media

Abstract

Objective: The role of pharyngeal lymphoid tissue in etiopathogenesis of secretory otitis is not yet defined. The influence of tonsillar and adenoid mass, weight, obstruction of naspharyngeal orrifitium, bacterial reservoire or some immunological events are of scientific interest. Tissue nonspecific alkaline phosphatase (TNAP) and acid phosphatase (ACP) are enzymes detected in lymphoid tissue, TNAP as characteristic of B cells, ACP as a characteristic of macrophages and folucullardentritic cells. These enzymes interfere in cell metabolism by removing 5' phosphate group from nucleotides and proteins. Specific activity and kinetic properties were studied in palatinal tonsils and adenoids of children with secretory otitis (OME) and compared with children with recurrent tonsillitis without ear involvement.

Method: Adenoid and tonsillar tissue of l7 children with OME and 30 children with recurrent tonsillitis were subjected to biochemical investigation using method of releasing of p-nitrophenol from p-nitrophenylphosphate (pNPP). Kinetic parameters as Michaelis-Menten constant were calculated by non-linear regression estimation method.

Results: Specific activity of adenoid alkaline phosphatase was lower in children with OME in relation to children with recurrent tonsillitis (t=5.733507, p<0.01). Specific activity of adenoid acid phosphatase was also lower in children with OME (t=3.655456, p<0.01). pH optimum for both enzymes was the same in these two groups of children. Michaelis-Menten constant for both enzymes was significantly higher in adenoid of children with OME than in children with recurrent tonsillitis suggesting lower enzyme affinity for the substrate.

Conclusion: Differences in specific activities and kinetic properties of adenoid alkaline and acid phosphatases between children with OME and children with recurrent tonsillitis without OME were verified in this study. The results of the study are not able to explain the alteration of alkaline and acid phosphatase characteristics but could point to some possible and specific role of nasopharyngeal lymphoid tissue in pathogenesis of secretary otitis.