Cytokeratin-immunoreactive cells of human lymph nodes and spleen in normal and pathological conditions

Summary The occurrence and the distribution of cytokeratin (CK)-immunoreactive reticulum cells in a series of normal and pathological human lymph nodes and spleens are documented. The immunoreactive cells exhibit morphological and immunophenotypic features of so-called fibroblastic reticulum cells, with or without myoid differentiation. They invariably co-express vimentin and, to a lesser extent, desmin and muscle-specific actin isoforms. These CK-immunoreactive cells are apparently a normal subpopulation of reticulum cells, being detectable from the early stages of spleen and lymph node development. They are distributed mainly in the paracortical and medullary regions of the lymph nodes and at the periphery of the white pulp in the spleen. Their number and distribution are highly variable in different neoplastic and non-neoplastic pathological conditions but the changes are not disease specific. CK-immunoreactive reticulum cells are easily identifiable in both frozen and fixed lymphoid tissue and in cytological smears of fine-needle aspirates, provided that monoclonal antibodies whose spectrum of reactivity includes cytokeratins 8 and 18 are used. The awareness of the occurrence of CK-immunoreactive cells in normal lymphoid tissues is of particular relevance in the search for micrometastatic foci using anti-CK antibodies.     

Extrafollicular reticulum cells in pathologic lymph nodes.

Extrafollicular reticulum cells in lymph nodes are heterogeneous. They express cytokeratins, desmin, and/or vimentin as their intermediate filament profile. Using those markers, we undertook an immunohistochemical study of human lymph nodes under various pathologic conditions. Samples included 15 simple reactive lymph nodes, 7 follicular hyperplasia, 1 necrotizing lymphadenitis, 4 tuberculous lymphadenitis, 13 malignant lymphoma (9 non-Hodgkin''s and 4 Hodgkin''s lymphomas), and 11 metastatic adenocarcinoma. In lymph nodes with follicular hyperplasia, cytokeratin and/or desmin expressing reticulum cells displayed a characteristic dendritic meshwork in the subcapsular, perisinusoidal, and paracortical regions. In other forms reactive lymph nodes, they were similarly distributed but were less prominent. By SDS-PAGE and immunoblotting, cytokeratin polypeptides were identified. In necrotizing lymphadenitis, they were increased and the pattern of distribution was disturbed. In tuberculous lymphadenitis, they were also increased and located at nongranulomatous as well as in perigranulomatous areas. In lymphomas the reticular meshwork was entirely obliterated. Cytokeratin or desmin expressing reticulum cells were rarely seen within tumors. The reticular meshwork was also obliterated in metastatic carcinoma. However, the meshwork was maintained in uninvolved areas. In conclusion, extrafollicular reticulum cells displayed characteristic patterns of distribution under various pathologic conditions, and may be implicated in the pathogenesis of those pathologic conditions in human lymph nodes.     

Benign vascular neoplasms of the spleen with myoid and angioendotheliomatous features

AIMS: To present the clinical light microscopic and immunophenotypic features of a distinctive vascular neoplasm of the spleen. METHODS AND RESULTS: Two of the splenic lesions arose in children, and one was found in an adult. They ranged from 19 to 40 mm diameter and histologically were quite similar. Sheets of large epithelioid cells with a spectrum of nuclear configurations ranging from oval and vesicular to twisted and hyperchromatic were noted in each case. Distinct or prominent nucleoli were present in many cells, and occasional cells had nuclear pseudoinclusions. In two cases, bands of basophilic, fibroblast-rich stroma with scattered chronic inflammatory cells were present. The mitotic rate ranged from 0/10 high-power fields (HPF) to 0.5/10 HPF in these epithelioid cells. The vascular nature of these tumours was manifested as a sieve-like array of round, erythrocyte-filled spaces, most with attenuated and cytologically bland lining cells. The polygonal, epithelioid cells exhibited the following phenotype: smooth muscle actin (SMA)+, muscle specific actin (MSA)+, vimentin+, CD31-, CD34-, CD21-, CD8-, CD68- (2/3 cases), S100-, while the lining cells were CD34+, vimentin+ and SMA-, with variable CD31 and factor VIII related antigen expression. Elongated SMA+, MSA+ cell processes were evident in one case, reminiscent of previously characterized myoid elements of the normal spleen. An uneventful follow-up was noted for all three patients. CONCLUSIONS: The histology and immunophenotype set these neoplasms apart from classic hamartomas, haemangiomas and previously characterized (haem)angioendotheliomas of the spleen, and may represent proliferations of myoid elements native to the spleen.     

Morphology of the spleen and lymph nodes in fatal visceral leishmaniasis.

Histological appearances of the spleen and lymph nodes were analysed in twenty fatal cases of human visceral leishmaniasis from Sudan. Marked atrophy of the splenic white pulp was associated with necrosis and fibrosis of thymus-dependent area, accumulation of parasite-containing histiocytes and plasma cell hyperplasia. Depletion of small lymphocytes in the paracortical areas of the lymph nodes was accomplained by proliferation of plasma cells and histiocytes in the paracortex. Depletion of small lymphocytes in thymus-dependent regions of lymph nodes and spleen is viewed as arising from immune suppression associated with antigen overloading or other factors, which may impair those aspects of lymphocyte-macrophage cooperation that are presumably necessary to kill the invading parasites.     

Difference in the functional maturation of T cells against Listeria monocytogenes in lymph nodes and spleen.

After subcutaneous immunization of mice with viable Listeria monocytogenes (LM), we evaluated the function of T cells induced in draining lymph nodes (LN) and spleen as determined by the local transfer of delayed-type hypersensitivity (DTH), acquired cellular resistance (ACR) and in vitro lymphokine production. LN cells could transfer specifically DTH but not ACR. In contrast, spleen cells from the same donor mice evoked the DTH response as well as bacterial clearance at the reaction site. Comparison of bacterial counts in spleen and in LN upon subcutaneous inoculation of mice with LM suggested that the lack of bacterial proliferation in LN underlay the failure to induce protective T cells in this lymphoid tissue. Spleen and LN T cells expressed CD4 and CD8 surface antigens equally and DTH response was solely dependent on CD4+ cells. Another major difference between LN and spleen cells was the profile of lymphokines produced in vitro. Upon the in vitro restimulation with killed Listeria, immune spleen cells produced macrophage chemotactic factor (MCF), interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). In contrast, LN cells could produce all of the measured lymphokines but not IFN-gamma. The results provided strong evidence for the dissociation of DTH and ACR. Listerial growth appeared to be the requirement for full maturation of anti-listerial immunity that may coincide with the generation of IFN-gamma-producing T cells.     

Comparison between the phenotype and function of maturing dendritic cells from spleen and lymph nodes.

We compared the capacity of mature dendritic cells (DC) from lymph nodes and maturing DC from spleens in their capacity to stimulate responses to the small hapten picryl sulphonic acid (PIC) and to the same hapten conjugated to ovalbumin (PIC-OVA) and requiring processing. Surface expression of major histocompatibility complex (MHC) class II molecules, which are upregulated during maturation of splenic DC, were studied as an independent marker of maturation. Freshly isolated lymph node DC had a veiled appearance and high levels of class II expression. DC separated from suspensions of spleen cells expressed the DC-specific marker NLDC-145, but were small, had low levels of MHC class II molecules and expressed stem cell antigen. Those DC from spleen cells cultured for 24 and 48 hr showed the development of typical veiled DC morphology and high class II expression. Lymph node DC stimulated high levels of primary T-cell proliferation to PIC, but failed to stimulate primary responses to PIC-OVA. Splenic DC isolated immediately failed to stimulate primary responses to either antigen. More mature spleen DC stimulated responses both to PIC and PIC-OVA. Surprisingly, development of the capacity to stimulate responses to PIC preceded that of stimulating PIC-OVA responses. The capacity of the DC to process and present PIC-OVA was maintained during the culture period. The results indicate that both the form of the antigen and the source and maturity of the DC are critical in determining the responses stimulated in T lymphocytes.     

Chemotaxis in normal and pathologic conditions

Under the influence of environmental chemical substances phagocytes are capable of directed migration towards chemoattractant concentration gradient (chemotaxis) and of increased speed of movement (chemokinesis). In the chain of events "triggered" by inflammation an important role is played by chemotaxis. The content of cell membrane enzymes, the level of cyclic nucleotides, mechanisms of ion transport, and ways of energy production change in response to the chemotaxic factor. Primary (congenital) and secondary (acquired) disorders of chemotaxis are distinguished. In detecting chemotaxis defects it is necessary to determine the capacity of cells for spontaneous migration in the absence of a chemical stimulation as well as the presence of serum inhibitors of chemotaxis. The study of cell receptor apparatus with the help of structurally defined chemotaxic factors as well as of the motor apparatus of the cell will give an insight into the concept of chemotaxis. At the same time, exerting an influence on chemotaxis simultaneously influences the inflammatory processes, therefore new approaches to treatment of inflammatory diseases may be developed by means of drugs modulating chemotaxis.     

Cellular distribution of dexamethasone in rabbit spleen and lymph nodes

The binding of tritiated dexamethasone by rabbit spleen and lymph nodes was studiedin vivo by dry radioautography. The labeled glucocorticoid was found in the surface and cytoplasm of eosinophil leukocytes and in the nuclei of reticular cells, plasmocytes, endothelial cells and macrophages, but not in lymphocytes, lymphoblasts or plasmoblasts. Additional administration of excess of excess of non-radioactive dexamethasone suppressed this labeling. The findings are discussed in relation to the mechanism of action of glucocorticoids in lymphoid organs.     

Occurrence of suppressor cells in lymph nodes and spleen at later times after immunization with contact-sensitizing agent picryl chloride.

The lymph node and spleen cells of mice painted on the skin with the contact sensitizing agent, picryl chloride, transfer contact sensitivity. Their ability to transfer reaches a peak 4 days after immunization and is absent by day 6 providing the recipient mice are challenged shortly after transfer (Chase type transfer). In contrast, when challenge of the recipients is delayed for 6 days (adoptive transfer), lymph node and spleen cells show the greatest ability to transfer 8-12 days after immunization. When cells taken 4 days after immunization (which transfer contact sensitivity) are mixed with cells taken at 6-11 days (which fail to transfer), the mixture shows little ability to transfer. This provides evidence for the occurrence of suppressor cells. Lymph node and spleen, and thymus cells show suppressor activity. The suppression is specific and cells from donors immunized with the contact-sensitizing agent oxazolone will not suppress passive transfer of contuse of the loss of ability of lymph node and spleen cells in transfer later than day 6 after immunization. Experiments on the loss of radioactivity from lymph nodes labelled with 125I-iododeoxyuridine (IUDR) suggest that loss of cells from the lymph nodes may be a contributory factor.     

K-cell cytotoxic activity in the spleen and lymph nodes of tumour-bearing mice.

The cytotoxic activity of spleen and lymph node cells from female CBA mice bearing a methylcholanthrene-induced fibrosarcoma on target cells coated with anti-target cell antibody has been investigated. Spleen cells from tumour-bearing mice caused a significantly greater degree of target cell lysis than did spleen cells from control mice. This increase in cytotoxicity was most apparent when a ratio of ten lymphoid cells to one target cell was used. With control mice, the mean cytotoxic index was 13.54 +/- 1.05 (s.e.m.) as compared to 55.00 +/- 6.11 with tumour-bearing mice. An increase in the cytotoxic activity of lymph node cells was also noted. In control mice, the cytotoxic index, using a ratio of 100:1 was 8.55 +/- 2.27. In tumour-bearing mice, the mean cytotoxic activity of the draining lymph node was 21.66 +/- 4.96, and of the contralateral lymph node, 13.00 +/- 3.46.     

Peliosis hepatis. An unusual case involving the spleen and lymph nodes

A case of peliosis hepatis in a 52-year-old woman with unusual involvement of the spleen and lymph nodes is described. The initial sign was intraperitoneal hemorrhage from the splenic lesion, recessitating splenectomy. The hepatic lesion, which was first noticed during the operation, rapidly progressed and eventually resulted in hepatic rupture with fatal intraperitoneal hemorrhage. Serial sections treated by silver impregnation revealed degeneration and dissolution of the fine reticulin framework in the involved organs, suggesting the possible morphogenesis of the peliotic lesion. The patient had no history of any underlying disorders or of medication with steroids.     

The T and B lymphocyte content of lymph nodes and spleen in Hodgkin's disease.

Lymphocytes from tumour-bearing lymph nodes in 15 patients with Hodgkin's disease, and lymphocytes from 6 spleens infiltrated by Hodgkin's tissue and 6 tumour-free spleens were studied using T and B lymphocyte markers. For comparison, lymphocytes from 16 tumour-free lymph nodes were similarly assessed. It was found that the tumour-bearing nodes showed a predominance of T lymphocytes compared with the control nodes, whereas in involved splenic tissue the proportion of T lymphocytes was slightly reduced compared with uninvolved spleens.     

Selective accumulation of cells with 'B' properties in stimulated lymph nodes.

Draining lymph nodes from mice which had been stimulated with bacterial adjuvants or the skin sensitizing agent, oxazolone, showed a marked increase in cell content, presumably due to lymphocyte immigration. A surprisingly large proportion of these cells exhibit properties of B lymphocytes: the presence of surface Ig, lack of Thy-1-like antigen and responsiveness to lopopolysaccharide (LPS). The relationship between the presence of surface markerand responses to class-specific mitogens, of cells from the stimulated nodes, was established by testing fractionated lymphocyte populations. Enriched T cells did not react to LPS, whereas removal of cells with Thy-1 antigen by specific antisera eliminated the reactions to T mitogens but had little or no effect on the LPS response. The data thus suggest that B cells, which make up a small portion of the circulating lymphocyte pool, are selectively accumulated in lymph nodes stimulated by different immunogens, including T-specific stimulants. This interpretation contradicts the generally accepted assumption, that stimulat lymph nodes trap mostly T lymphocytes.     

Studies of efferent lymph cells from nodes stimulated with oxazolone.

Efferent lymph from nodes regional to areas of skin that had been treated with solutions of oxazolone in acetone was collected from unanaesthetized sheep. The application of 5% solutions of oxazolone to unsensitized sheep caused no signs of acute inflammation or ''shut-down'' of lymphocyte traffic; none the less, normal immune responses ensued so that immunoblasts, some containing immunoglobulin, were discharged into the lymph together with specific humoral antibodies. When previously sensitized sheep were challenged with 2.5% solutions of oxazolone the vigorous secondary responses were heralded by Arthus reactions, induced presumably by pre-existing antibodies, which were mainly of the IgG class. A similar sequence of events occurred in a thymus-deprived sheep which had undergone intra-uterine thymectomy at 60 days of gestation. Repeated applications of oxazolone to normal sheep did not exhaust or inhibit the characteristic changes in the flow and composition of the lymph. When immunoblasts from efferent lymph were radiolabeled with 125I-UdR and returned intravenously to the sheep they showed no significant tendency to localize either specifically or non-specifically in areas of skin that had been treated with contact-sensitizing chemicals.