Superoxide dismutases in human palatine tonsils

In order to investigate the protective system of human palatine tonsils against the cytotoxic superoxide radicals (O₂^-) generated from the oxygen-related bactericidal system, immunohistochemistry and electron spin resonance (ESR) spectrometry were used to detect the distribution and activities of superoxide dismutases (SODs) in tonsils of different related systemic diseases. Immunohistochemistry showed that SODs distribute in extrafollicular lymphatic tissue and crypt epithelium. No distribution difference could be found between tonsils of different related systemic diseases. ESR revealed no significant difference between SODs activities in tonsils of different related systemic diseases. However, the mitochondrial SOD activity was found to constitute approximately 50%-60% of the total tonsillar cellular SODs activity. The results suggest: i) tonsils possess the ability to control cytotoxic O₂^-, ii) crypt epithelium and extrafollicular lymphatic tissue may encounter more O₂^- threat, iii) SODs may be important in protecting germinal centers from O₂^- injury, and iv) systemic diseases are less related to the local expression of tonsillar SODs.