The paracortical area in reactive lymph nodes demonstrating sinushistiocytosis. An enzyme- and immunohistochemical study

Significance of S-100 Protein Immunostaining in the Immunohistological Analysis of Normal and Neoplastic Lymphoid Tissues - An Appraisal

S-100 protein is a heterogeneous fraction of dimeric polypeptides (alpha and beta subunits) that can exist in different combination forms within the various tissues. Concerning the S-100 protein immunodetection within lymphoid tissue, the heterogeneity of the S-100 antigen, the tissue quality (frozen or paraffin-embedded after treatment with different fixatives) and the treatment of the tissue with different immunostaining methods and antibodies of different nature, all make for inconsistent results obtained in the immunohistological studies reported in the literature. Most of the S-100-positive cells of the lymphoreticular system are dendritic cells involved in the immune response (interdigitating reticulum cells, Langerhans cells, and follicular dendritic reticulum cells), other S-100-positive cells belonging to the mononuclear/phagocytic system. S-100 protein immunostaining may be used as a helpful immunohistological diagnostic clue to certain malignancies of the immune system (follicular center cell lymphomas) on the basis of their specifically related dendritic cell microenvironment. In addition to monoclonal antibodies for the immunophenotypic characterization of dendritic cells and macrophages and to enzyme reactions, the combined use of anti-S-100 antibodies specific for each of the S-100 protein subunits, tested with sensitive procedures, would be a very useful tool in the attempt to classify the proliferative disorders of dendritic cells and macrophages.

The morphology, immunophenotype and distribution of paracortical dendritic leucocytes in lymph nodes regional to cutaneous melanoma

Our aim was to identify and delineate alterations in the distribution and immunophenotype of the lymphocytes and paracortical dendritic leucocytes (interdigitating dendritic cells; IDCs) in lymph nodes regional to tumours. Using immunocytochemistry and computer-assisted image analysis we examined 65 lymph nodes excised from 47 patients with malignant melanoma. Twenty-nine patients had American Joint Committee on Cancer (AJCC) stage II melanoma (no tumour spread beyond the primary site) and 18 had AJCC stage III disease (metastases in the regional nodes). There were significant differences in the frequency, morphology, immunophenotype and anatomical distribution of the IDCs and in the complexity of their dendritic processes in different areas within individual lymph nodes. We conclude that morphological and phenotypical variations in IDCs correlate with differing levels of antigen presentation. Downregulation of antigen presentation in lymph nodes regional to tumours is most probably mediated by tumour products. Differences in IDC distribution and characteristics in lymph nodes from different anatomical sites must be considered in interpreting studies of nodal morphology and function.

Interdigitating cell sarcoma (ICS). Evidence of interdigitating cell origin, immunocytochemical studies with monoclonal anti-ICS antibodies

Three independent mouse monoclonal antibodies (mAbs) ID1 (IgG3), ID2 and ID3 (IgM) were raised against whole cells of a surgically resected human interdigitating cell sarcoma (ICS). In immunoperoxidase staining, these mAbs strongly stained the cytoplasm of ICS neoplastic cells as well as interdigitating cells in normal lymphoid tissues. These mAbs also detected monocyte/macrophages and dendritic cells, although their staining was highly variable depending on tissue distribution of the cells. Additional immuno-histological and enzyme histochemical study revealed that the neoplastic cells of ICS had cytoplasmic acid phosphatase and membranous alkaline phosphatase activity, and also possessed S100 beta protein, Ki-1 antigen. DAKO-macrophage antigen, and weak vimentin activity. Neither rearrangement of immunoglobulin heavy chain gene nor of T-cell receptor genes was detected in the DNA of ICS by Southern hybridization. These observations provide further confirmation of our previous finding (Nakamura et al. 1988, 1989) that the origin of ICS is interdigitating rather than lymphoid cell, and indicate that our mAbs could be useful as a cellular differentiation marker of interdigitating cells and for diagnosis of ICS.

Immunophenotypic characterization of mononuclear phagocytes and dendritic cells in lymphoid organs of the rhesus monkey

Mononuclear phagocytes and dendritic cells are potent antigen-presenting cells that localize to distinct microenvironmental compartments in many different organs. These cells are particularly plentiful in spleen and lymph node. Recently, these cells have been identified and immunophenotypically characterized in human tissue sections using monoclonal antibodies. However, similar studies in animal species, particularly those representing models of human diseases, have yet to be completely performed. We have evaluated 18 monoclonal reagents raised against human determinants for their reactivity with macrophages and dendritic cells in lymphoid organs of rhesus monkeys. Six of the 18 (EBM11, 25F9, Mol, R4/23, To5, and SK9) produced labeling patterns in rhesus monkey lymphoid tissue that paralleled the staining patterns described for human tissues. Seven others (KB90, FMC17, Mo3, PHM3, PHM2, G16/1, and 27E10) stained varying subsets of specific cells types in these simian tissues. These reagents are requisite for the future study in an experimental animal of the afferent immune response in both normal and disease states.

Sarcoma arising from interdigitating reticulum cells: report of a case, studied with light and electron microscopy, and enzyme- and immunohistochemistry

The morphological, enzyme- and immunohistochemical features of a sarcoma arising from interdigitating reticulum cells (IDRC) are presented. These cells are normal constituents of the T-dependent region of lymphoid organs, and their function is largely unresolved. The immunohistochemical findings in the present case indicate that neoplastic IDRC are morphologically and phenotypically similar to normal IDRC in lymphoid organs. Functionally however, neoplastic IDRC more closely resemble IDRC in the fetal lymph node and in the thymus, where they are thought to play a role in the final differentiation of immature thymocytes into mature peripheral T-lymphocytes.

Role of the regional lymph node in cancer metastasis

At an early phase of tumor growth, T-cell responses, i.e. the proliferation of T cells and the generation of cytotoxic T cells or killer-augmenting T cells are induced in the regional lymph node depending upon the immunological properties of the tumor cells. A small number of tumor cells seems to be rejected in the regional lymph node in situ. A progressive tumor induces suppressor activity in the regional node. Suppressor cells facilitate tumor growth and lead to lymphatic metastasis. Thus, the regional lymph node operates only as a temporary barrier to tumor growth. Experimental studies have demonstrated that eradication of the suppressor cells and effective immunization, or both, lead to tumor rejection by augmenting the immunological activity of the regional lymph node.