P. Eikelenboom

Characterization of non-lymphoid cells in the white pulp of the mouse spleen: an in vivo and in vitro study

SummaryNon-lymphoid cells (marginal metallophils, follicular immunecomplex-retaining cells, interdigitating cells), which are present in certain areas of the white pulp in the mouse spleen were characterized by means of (immuno)enzyme histochemical techniques, carbon uptake and experiments with lethal X-irradiation. Marginal metallophils are clearly present at the inner border of the marginal zone and show a very strong, E-600 sensitive, non-specific esterase (NSE) activity. Follicular immune-complex-retaining cells show a weak and diffuse NSE activity and no carbon uptake as shown by the combined application of an immunohistoperoxidase technique (for the demonstration of immune complexes), enzyme histochemistry (for NSE activity) and carbon uptake (for phagocytosis). Interdigitating cells show a distinct focus of NSE activity in the cytoplasm, weak carbon uptake and high radiation sensitivity. Demonstration of NSE activity is useful for the identification of the different non-lymphoid cells in the white pulp of the mouse spleen. It is suggested that the in vitro observed dendritic cells of Steinman and Cohn (1973) belong to the mononuclear phagocyte system, as “transitional cells” are encountered with cytological features of both dendritic cells and macrophages. These in vitro dendritic cells (or a portion of them) are probably similar to the interdigitating cells.

Characterization of lymphoid and nonlymphoid cells in the white pulp of the spleen using immunohistoperoxidase techniques and enzyme-histochemistry

The main function of the lymphoid system is to offer an opportunity for immune reactions against foreign substances or organisms. In vitro studies show that both T and B lymphocytes as well as mononuclear phagocytes are essential for most types of immune responses. In vivo the interaction between antigen, T lymphocytes, B lymphocytes and mononuclear phagocytes takes place within a frame-work of reticular cells in the peripheral lymphoid organs; the outcome of these interactions is likely to be determined by the precise micro-environment situation in which they meet 31. In the peripheral lymphoid organs T and B lymphocytes are located in defined compartments which are also populated by characteristic nonlymphoid cells 26,5~176 The (sub)classes of lymphocytes can be defined by their surface determinants and visualized with irmnunohistoperoxidase methods. At the light microscopical level nonlymphoid cells are mostly characterized by their enzyme histochemical properties and/or functional capacity. At the moment an increasing number of monoclonal antibodies against antigens present on reticular elements is becoming available ~. These antigens are mostly shared by several lymphoid and nonlymphoid cells. A useful tool to distinguish between these different cell types is the combination of immunohistoperoxidase techniques and enzyme histochemistry on the same section. The aim of this paper is to illustrate the possibilities of immunohistoperoxidase techniques in morphological studies of the white pulp. A review is presented on the characterization and localization of lymphoid cells and, particularly, nonlymphoid cells in the white pulp, using immunohistoperoxidase techniques and enzyme histochemistry. The antigen-induced transformation of lymphocytes to plasma cells is also described.

The development of IgM- and IgG-containing plasmablasts in the white pulp of the spleen after stimulation with a thymus-independent antigen (LPS) and a thymus-dependent antigen (SRBC)

SummaryThis study describes the development of IgM and IgG containing plasmablasts in splenic white pulp after a single intravenous injection of the thymus-independent antigen lipopolysaccharide (LPS) or the thymus-dependent antigen sheep erythrocytes (SRBC) using immunohistoperoxidase techniques.Attention has been paid especially to the sites where IgM and IgG blasts develop in the white pulp and their migration route, from the white pulp towards the red pulp. The distribution of IgM and IgG blasts in the different white pulp compartments, i.e. outer periarteriolar lymphocytic sheath (PALS), inner PALS, follicles and the area along the terminal arteriolar branches, has been studied. Our findings indicate that both the thymus-independent IgM response to LPS and the thymus-dependent IgM response to SRBC start in the outer PALS. During the course of the immune response against SRBC the early localization of IgG plasmablasts in the white pulp was dispersed through the whole PALS. Later in the immune response the IgG blasts in the white pulp were localized especially in and at the border of follicle centres. No significant development of IgG blasts was found after LPS administration. The results of the present study suggest that during the immune response the bulk of IgM blasts migrates via the outer PALS and along the terminal arteriolar branches into the red pulp.

Immune complex-trapping cells in the spleen of the chicken

SummaryBy 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 complextrapping 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.

Dendritic cells in the rat spleen follicles

SummaryFollicles of peripheral lymphoid organs (rat) contain a type of non-lymphoid cell which is capable of arresting antigen-antibody complexes at the cell surface. These so-called dendritic cells can be visualized in immunized rats by staining antigen-antibody complexes with immunohistoperoxidase techniques.The present study concerns a classification of these cells and comparison with known non-lymphoid cell types such as macrophages, marginal metallophils and tingible body macrophages in the rat spleen follicles. Immunoenzyme histochemical and (enzyme) histochemical techniques have been combined in the same tissue sections to correlate the functional capacity of binding immune complexes with morphological characteristics or phagocytic capacity. Dendritic cells show silver affinity but do not demonstrate a characteristic pattern of hydrolytic enzymes or phagocytosis.