Immunohistochemical localization of cytokines and receptor-associated molecules in human tonsils and skin

Human tonsilla palatina and skin were investigated by means of light microscopical and electron microscopical immunohistochemistry using monoclonal antibodies (Mab) against some cytokines. In both tonsils and skin we found intracellular immunoreactivity for interleukin-1-beta in macrophages and interdigitating cells. Also some, but not all crypt-epithelial cells were positive, while keratinocytes in the skin were negative. Interleukin-2-immunoreactivity was found in a subpopulation of lymphocytes (probably T-cells) and unexpectedly also in some antigen-presenting cells (APCs). A Mab against interleukin-4 revealed weak labelling of lymphatic cells in the T-cell area of tonsils. The human skin was negative. A Mab that recognizes a molecule associated with the interleukin-4-receptor gave strong surface labelling in tonsils and skin on APCs and weak immunoreactivity on lymphoid cells. Frequently these APCs formed rosettes with weakly labeled lymphocytes. Mabs against interleukin-8 stained starry sky macrophages in the germinal centers of the tonsil and different APCs in the T-cell region. IL-8 is stored in keratinocytes of normal skin, but becomes mobilized under inflammatory conditions. Our results expand the understanding of cell cell-interactions under normal and inflammatory conditions in tonsil and skin.