gms | German Medical Science

The significant position of palatine tonsils implies a key role as secondary lymphoid organ in initiating immune responses against various airborne and food-derived antigens. However, little is known about specific allergic immune responses and their influence on the composition of secondary lymphoid follicles in human palatine tonsils. Here we investigated the impact of an allergen-specific immunreaction on the morphology and composition of secondary lymphoid follicles.

Using immunohistological methods, CD20+-, CD38+-, CD4+-, Ki67+-and IgA-containing cells were stained in cryosections and the distribution of proliferating- and Ig-containing cells in different compartments was analyzed.

Our analyses have shown a differential expression and distribution of IgA- plasmacells in tonsils of allergic patients. The amount was diminished in allergic patients. Further, in allergic and non- allergic patients the number of secondary lymphoid follicles was increased and morphologic differences especially an increased amount of proliferating cells, compared with healthy individuals, were shown. However, tonsils of healthy persons and both patient groups were comparable concerning their typical morphologic structures, size of follicles and B- and T cell distribution in the different microcompartments.

Altogether, these data may lead to the assumption that the reduction of IgA-positive plasmacells within the epithelial microenvironment of the crypts and extrafollicular areas in allergic individuals results in a reduced ability to mount a protective immune response against allergens. The increased number of follicles together with the high number of proliferating cells in the tonsillar GC of the patient groups may reflect the ongoing GC- reaction induced by an increased antigen stimulation.