The distribution of some components of complement, immunoglobulins and lysozyme in the tonsil has been investigated by the immunofluorescent techniques. Intercellular spaces of the epithelium of free surface contained Clq in 35.7% of examined cases, Cis in 59.1%, C4 in 83.9%, C3 in 60.0%, C3PA (Factor B) in 52.6% and C3a in 81.8%. These spaces also contained IgG in 27.3% of examined cases, IgA in 63.0%, IgE in 53.8%, IgD in 38.1% but IgM only in 7.1%. The distribution of components of complement and immunoglobulins in the epithelium of crypts was much the same as that of free surface. Lysozyme was observed on the surface of the epithelium and in the debris of crypts. In very rare cases, it was localized in the intercellular spaces of upper layer of the epithelium.
Germinal centers of the tonsil showed C3 in 80.0% of examined cases and C4 in 69.2% in the interstitial spaces, but showed little Clq, Cis, C3PA and C3a. IgG-, IgM-, IgA and IgE-contained germinal centers could be observed but IgD-contained ones were never observed. On the contrary the cap area, a cuff of tightly packed small lymphocytes adjacent to the germinal center toward to the epithelium, contained only IgM and IgD.
Those observations suggest that the tonsil has self-defence mechanisms in the epithelium and that the role of C3 and C4 in the germinal centers is related to the progressive capture and aggregation of lymphocytes at the surface of antigen-binding dendritic cells. The presence of IgM and IgD in the cap area is in accordance with the hypothesis of the differentiation of bone marrow-derived lymphocytes.
View full abstract