[Comparative immunocytochemical studies of recurrent tonsillitis and infectious mononucleosis].

72 patients suffering from recurrent tonsillitis, and ten with infectious mononucleosis were compared by morphological and immunological studies. The distribution of Ig-containing plasma cells (IgA, IgG, IgM), lambda- and kappa-chains, lysozyme and Alpha-1-antitrypsin in tonsils was determined by the unlabelled antibody peroxidase-antiperoxidase method and correlated with the structure of the tonsils (follicles, interfollicular area, and reticular epithelium). While recurrent tonsillitis was associated with slight follicular hyperplasia, infectious mononucleosis was characterised by a marked distortion of the tonsillar architecture, reduction in the number of follicles and a mixed cellular proliferation. The cellular infiltration was composed of small, well differentiated lymphocytes, atypical lymphocytes (Downey cells), plasma cells, immunoblasts, and a variable number of pleomorphic immunoblasts (Reed-Sternberg-like-cells). The binucleated or multinucleated immunoblasts contained IgA, IgG, and IgM. Ig-producing cells occurred in all compartments. In recurrent tonsillitis most were found in the reticular epithelium, but in infectious mononucleosis their density was highest in the interfollicular area. There was a general prominence of IgG cells, confirming that the tonsils resemble lymph nodes more closely than the lymphoid tissue of the alimentary tract. Cells containing lambda and kappa chains were found in all follicle centres and extra-follicular areas. They gave evidence of polyclonality in both diseases. Lysozyme and Alpha-1-antitrypsin were present only in the vessels.