Immunologically induced changes in the tonsillar crypt epithelium

Functional architecture of the nasopharyngeal tonsil

The exact architecture of the normal nasopharyngeal tonsil remains obscure because most histopathologic investigations have been based on surgically removed adenoids. We compared enlarged adenoids and normal nasopharyngeal tonsils under both light and electron microscopes. The marked features of clinically enlarged adenoids were a large extension of the reticular epithelium and increased germinal centers. A tendency toward increased stratified squamous epithelium and decreased ciliated epithelium was apparent in enlarged adenoids, possibly due to inflammatory conditions. One type of nonciliated cell seemed to transport foreign material into underlying lymphocytes, as do the M cells of gut-associated lymphoid tissue. This type of nonciliated cell was rarely found in the extended reticular epithelium of enlarged adenoids. These findings suggest a disturbance of the antigen-trapping system and surface protections in adenoidal enlargement.

Antigenic determinants detected on adenoid lymphocytes

This study was undertaken to detect the antigenic determinants expressed by adenoid lymphocytes. For this purpose, adenoid and peripheral blood lymphocytes obtained from the same patient were subsequently tested with human and hetero antisera. The research was based upon microlymphocytotoxicity where the various lymphocyte subsets were incubated with the antiserum and complement. The reactions were scored by the dye exclusion technique. The results indicated that: 1) compared with peripheral blood, the expression of the major histocompatibility gene products is enhanced by adenoid lymphocytes; 2) adenoid T lymphocytes express DRw antigens. These antigens were thought to be restricted to B lymphocytes and macrophages but have later been detected in T lymphocytes activated in vitro. Thus, lymphocytes derived from hypertrophied adenoids may simulate a culture activated in vivo; 3) because of their higher sensitivity to antibodies and complement-mediated cell lysis, adenoid lymphocytes may be useful in detecting minor histocompatibility gene products and differentiation antigens. It is concluded that adenoids represent a highly active lymphoid organ probably actively participating in the host's immunological defence mechanism.