Immune complex-trapping cells in the spleen of the chicken. Enzyme histochemical and ultrastructural aspects.

By means of immunohistoperoxidase techniques and the use of HRP-anti-HRP complexes, follicular dendritic cells in chicken spleen can be characterized both at the light-microscopical and ultrastructural level. In contrast to findings in mammals follicular dendritic cells in chicken spleen exhibit evident acid-phosphatase activity and possess considerable numbers of primary lysosomes. After intravenous injection of immune complexes a transient immune complex-trapping occurs in the peripheral parts of the Schweigger-Seidel sheath. The immune complex-trapping cells in the Schweigger-Seidel sheath and germinal centre show an identical enzyme histochemical pattern and only minor differences in ultrastructural characteristics. Shortly after intravenous injection of immune complexes and carbon particles these compounds show an identical distribution pattern; however, in the following days these distribution patterns become divergent.