Melatonin restores and enhances the human type B tonsillar lymphocyte subset in recurrent acute tonsillitis

Tonsils have a privileged situation in the immune system in that they are in touch with the environment. Melatonin is a hormone that is influenced by the circadian environmental variations of dark-light and is a modulator of the immune system. We have studied a group of thirty five children with recurrent acute tonsillitis that were submitted for tonsillectomy. Tonsillar lymphocyte subsets were determined before and after culture through flow cytometry in a tonsillar mononuclear suspension. After the culture, the lymphocyte subsets of type B suffered a decrease that was restored in the presence of melatonin or phytohemaglutinin, and even increased above the values of the control when the culture was accomplished in the presence of both substances. This process was specific for B cells, no occurrence for T lymphocytes or natural killer cells. Melatonin is found in the crossroads of the interaction of the microorganisms, pollens or inert substances with the tonsillar lymphocytes in the production of the immune defences. Further study is required on tonsillar pathology to explain its physiopathology and its possible therapeutic role.