Comparison of mycobacterial granulomas guinea-pig lymph nodes

A study was made of mycobacterial-induced granulomas in guinea-pig lymph nodes. Live BCG (Pasteur) induced a granuloma containing epithelioid cells while Cobalt irradiated Mycobacterium leprae induced a granuloma comprised of phagocytic macrophages. The granulomas were quantitated by measurement of lymph node weight and the areas of infiltration in histological sections. The time course of granuloma formation induced by Co-irradiated M. leprae was very different from the time course of the granuloma formation induced by BCG. Collagen synthesis assessed by incorporation of ¹⁴C-proline into collagenase sensitive protein was greater in lymph nodes draining the site of injection of Co-irradiated BCG than those draining the site of injection of Co-irradiated M. leprae during the first 10 weeks. Collagen synthesis was delayed in the nodes from animals injected with live BCG for at least 10 weeks. Single cell suspensions of draining lymph nodes containing granulomas consisted of lymphocytes and large cells (epithelioid cells and macrophages). A high proportion of the large cells were found to be non-adherent in the live BCG-induced epithelioid cell granuloma. In contrast, M. leprae-induced granulomas contained a high percentage of adherent large cells. In both the granulomas, the majority of large cells were esterase positive and showed the presence of fibronectin. Most of the large cells in the granulomas did not carry receptors for the Fc component of IgG or the C3 component of complement and did not exhibit peroxidase activity.     

A mature thymocyte-like phenotypic pattern on human cord circulating T-lymphoid cells

Cord blood samples from healthy full-term newborns were tested with antimature and antiimmature lymphoid-cell monoclonal antibodies, as well as more traditional markers, in order to identify the phenotype of circulating precursor cells. The results demonstrated that human cord blood contains a lower number of OKT3⁺, E-rosetting mature T cells than adult blood, very high levels of OKT10⁺ cells, and few OKT9⁺, OKT8⁺OKT3^–, and OKT4⁺OKT3^– cells. Although the finding of OKT9⁺ and OKT10⁺ cord circulating cells could be indicative of cell activation, double marker studies in newborn blood pointed to phenotypically immature lymphoid subsets at different stages of maturation, according to Reinherz's hypothesis. In addition, the absence of nuclear Tdt-positive and hot-rosetting cells, together with the fact that most of these are OKT3⁺, OKT10⁺, OKT4⁺, or OKT8⁺ cells, suggests that the surface phenotype of newborn lymphocytes is similar to that of mature thymocytes.     

Giant cell formation in sarcoidosis: cell fusion or proliferation with non-division?

Granulomas are inflammatory reactions featuring macrophages, epithelioid, T and multi‐nucleated giant cells (MGC). Giant cells are present in a number of granulomatous reactions, but little is known about their formation and function, especially in man. We studied MGC in the granulomatous disorder sarcoidosis. In situ labelling of lymph nodes by means of [³H]‐thymidine showed that proliferation and non‐division of epithelioid cells leading towards giant cells was not observed in these granulomas. However, [³H]‐uridine incorporation showed MGC with labelled as well as unlabelled nuclei in the same cell, pointing to a process of fusion of epithelioid cells to form giant cells. Apoptotic bodies were incidentally found in granulomas. A novel finding was that such bodies were statistically more often found in the close vicinity of MGC, but not within these cells. These apoptotic cells appeared to be CD4⁺ lymphocytes or histiocytes. CD44 and CCR‐5 involved in the process of fusion were expressed in MGC. In conclusion, MGC in sarcoidosis derive by cell fusion rather than by proliferation and non‐division, and seem to play an active role in the induction of apoptosis in granulomas.     

Application of in-vitro techniques to determine proliferation in human sarcoid lymph nodes

Sarcoidosis is suggested to be a granulomatous disease with high-turnover characteristics. In this paper the turnover of the inflammatory cells (the epithelioid cells) in lymph node granulomas from sarcoidosis patients is described. Uniform slices of granulomatous lymph nodes were incubated with ³H-thymidine; autoradiographically the DNA-synthesizing cells, parameter for local proliferation, were detected and the L.I. (labelling index) was determined. We observed mostly low-turnover reactions, incidentally granulomas with high-turnover characteristics are found within the same lymph node. The uptake of ³H-TdR demonstrates that these granulomas could be in different stages of activation.     

In situ immunological characterization of Langerhans cells with monoclonal antibodies: Comparison with other dendritic cells in skin and lymph nodes

Summary The antigenic properties of epidermal Langerhans cells (LC) were determined and compared with those of non-lymphoid dendritic dermal cells (DDC), interdigitating reticulum cells (IRC), dendritic reticulum cells (DRC), and histiocytic reticulum cells (HRC) by examination of serial and double immunoenzymatic and -fluorescence stained frozen sections of skin and lymph node biopsies.All of these cell types expressed leucocyte common antigen. LC, DDC, and IRC demonstrated similar antigenic phenotypes (HLA-DR⁺, Leu3⁺, OKT6^+/–, anti-C3 receptor^–, R4/23^–, Ig-complex^–, M02^–), whereas the antigenic properties on DRC (HLA-DR^–, Leu3^–, OKT6^–, anti-C3 receptor⁺, R4/23⁺, Ig-complex⁺, M02^–) and HRC (HLA-DR^+/–, Leu3^–, OKT6^–, anti-C3 receptor⁺ R4/23^–, Ig-complex⁺, MO2⁺) were markedly different.These data suggest that LC, DDC, and IRC are closely interrelated cell types, and support the concept that DRC and HRC are unique cell types which do not appear to be related to LC, DDC, or IRC. The lack of labelling of LC with monoclonal anti-C3b receptor antibody, and polyclonal antiserum recognizing C3b, C3bi, and C3d receptors strongly indicate that the EAC-rosetting of LC previously described is not due to the presence of C3 receptors on these cells. Alternatively, LC may express C3 receptor molecules different from those previously identified (C3b, C3bi, and C3d).     

The comparative evaluation of immunohistochemical and acid fast staining with histopathological changes in naturally occurring paratuberculosis in sheep

Histopathological changes and degrees of positivity by Ziehl–Neelsen (ZN) and avidin–biotin complex peroxidase (ABC) techniques were studied in 29 adult sheep grossly or clinically suspected to have paratuberculosis. Of these, 16 (55.1%) had microscopic lesions associated with paratuberculosis, which were classified into 4 categories. Focal–multifocal lesions (6.9%) consisted of small granulomas in the lamina propria of the ileum especially in the ileocecal Peyer’s patches and also in the mesenteric lymph nodes. Diffuse multibacillary lesions (31%) characterized by a diffuse granulomatous enteritis with epithelioid macrophages infiltration as main inflammatory cells that arranged in mosaic-like appearance, filled with numerous acid fast bacilli in ZN, and highly positive in ABC. Diffuse paucibacillary (lymphocytic) lesions (6.9%) composed of lymphocytes as main inflammatory infiltrate with some epithelioid macrophages or giant cells containing few if any mycobacteria. Diffuse intermediate (mixed) lesions (10.3%) characterized by a diffuse granulomatous enteritis with infiltration of large numbers of lymphocytes and also epithelioid macrophages with varying degrees of positivity in ZN and ABC. In the diffuse lesions, other lesions such as granulomatous or lymphocytic lymphangitis, lymphangiectasis, intravascular aggregates of epithelioid macrophages, lymphocytic infiltration around the myenteric nerve ganglia, severe granulomatous arteritis, atherosclerotic-like lesions and vascular thrombosis especially in the capsule of mesenteric lymph nodes, and serosal layer of intestine were observed. We could not find any necrotic or calcified lesion in the intestinal tissues of affected sheep but we found a few small foci in the mesenteric lymph nodes of two cases. High numbers of multinucleated langhans giant cells were seen only in mesenteric lymph node of one affected sheep. In conclusion, the present study showed four categories of lesions in which multinucleated giant cells, necrosis, and calcification were uncommon particularly in the intestine. Both immunohistochemistry (IHC) and ZN methods can detect IHC with more positivity in almost all the sheep with diffuse lesions; more cases with focal and paucibacillary forms were positive by IHC than by ZN. The importance of sampling the ileum (especially ileocecal valve), jejunum, and mesenteric lymph nodes to find microscopic lesions of paratuberculosis in sheep is emphasized.     

Immunohistochemical study of bovine lymph nodes with antibodies against S100 protein subunits: Comparison between lymph nodes of healthy and Mycobacterium paratuberculosis-infected cattle

Using immunohistochemistry, the differential distribution of the α subunit (S100α) and β subunit (S100β) of S100 protein was studied in mesenteric lymph nodes from normal or Mycobacterium paratuberculosis-infected cattle. In epithelioid cell granulomas, S100α-positive epithelioid cells and some giant cells were scattered among S100α-negative cells, which were predominant. The S100β-positive and -negative cells contained acid-fast bacilli. The presence of S100β-positive cells was not demonstrated in the granulomas. In normal component cells in the lymph nodes, follicular dendritic cells in the germinal centres and endothelium of lymphatic sinus and lymph vessels were positive for S100α. S100β was positive only in the endothelial cells of blood vessels. Results shown in the present paper are discussed in light of results obtained in other work on human tissues using the same sources of antibodies.     

Phenotype, functions and fate of adoptively transferred tumor draining lymphocytes activated ex vivo in mice with an aggressive weakly immunogenic mammary carcinoma

Background

Regression of established tumors can be induced by adoptive immunotherapy with tumor draining lymph node lymphocytes activated with bryostatin and ionomycin. We hypothesized that tumor regression is mediated by a subset of the transferred T lymphocytes, which selectively infiltrate the tumor draining lymph nodes and proliferate in vivo.

Results

Adoptive transfer of B/I activated tumor draining lymphocytes induces regression of advanced 4T1 tumors, and depletion of CD8, but not CD4 T cells, abrogated tumor regression in mice. The predominant mediators of tumor regression are CD8+ and derived from CD62L^- T cells. Transferred lymphocytes reached their peak concentration (10.5%) in the spleen 3 days after adoptive transfer and then rapidly declined. Adoptively transferred cells preferentially migrated to and/or proliferated in the tumor draining lymph nodes, peaking at day 5 (10.3%) and remained up to day 28. CFSE-stained cells were seen in tumors, also peaking at day 5 (2.1%). Bryostatin and ionomycin-activated cells proliferated vigorously in vivo, with 10 generations evident in the tumor draining lymph nodes on day 3. CFSE-stained cells found in the tumor draining lymph nodes on day 3 were 30% CD8⁺, 72% CD4⁺, 95% CD44⁺, and 39% CD69⁺. Pre-treatment of recipient mice with cyclophosphamide dramatically increased the number of interferon-gamma producing cells.

Conclusions

Adoptively transferred CD8+ CD62L^low T cells are the principal mediators of tumor regression, and host T cells are not required. These cells infiltrate 4T1 tumors, track preferentially to tumor draining lymph nodes, have an activated phenotype, and proliferate in vivo. Cyclophosphamide pre-treatment augments the anti-tumor effect by increasing the proliferation of interferon-gamma producing cells in the adoptive host.     

Induction of cytotoxic T lymphocytes specific to the molecule of the class I major histocompatibility complex for subcutaneous immunization in pads

T lymphocytes from immune lymph nodes, specific to the molecule of the class I major histocompatibility complex, were found to contain cytotoxic T lymphocyte precursors which mature to become effector cytotoxic T lymphocytes only in the presence of helper cells and L3T4⁺, but not Lyt2⁺ T helpers. The findings indicate that a subcutaneous injection of alloantigen of the class I major histocompatibility complex for immunization in the pads leads to the creaction of the type of microenvironment of the lymph nodes which prevents activation of Lyt2⁺ T helpers or leads to the activation of their functionally negligible part. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, pp. 190–193, February, 1995 Presented by N. N. Trapeznikov, Member of the Russian Academy of Medical Sciences     

Dendritic Cells in Cutaneous, Lymph Node and Pulmonary Lesions of Sarcoidosis

To determine whether dendritic cells (DC) are a consistent feature of lesions of sarcoidosis, we have used monoclonal antibodies to identify the HLA-DR-expressing populations of cells in cryostat sections of 15 lymph node, pulmonary and cutaneous lesions. The commonest HLA-DR positive cells in granulomas were epithelioid and giant cells, although lymphocytes within granulomas and tissue macrophages around them were also positive. Dendritic cells with Langerhans cells (NA1/34+ = OKT6+) and interdigitating cell (RFD1+) phenotype were consistently associated with granulomas only in skin lesions. In lymph nodes, interdigitating cells (NA1/34-/RFD1+/HLA-DR++) were confined to paracortical zones as in normal nodes, although a small area of NA1/34+/RFD1+ cells was found in one of three nodes. In lung lesions NA1/34+/RFD1+ dendritic cells were uncommon or absent, except in one chronic case. We conclude that while sometimes present in extracutaneous sites, DC are not an essential feature of sarcoid lesions, and that cells of the classical macrophage group are the most significant HLA-DR-expressing population. We suggest that the presence of DC in lesions of sarcoidosis may indicate an immunological response distinct from that causing granulomas to form. The variability of their involvement may have immunoregulatory significance.     

Immunohistological findings of suppurative granulomas of Yersinia enterocolitica appendicitis: a report of two cases

We report on the histopathologic and immunohistologic findings of two cases of suppurative granulomatous appendicitis of Yersinia enterocolitica (Y. ent.). Using formalin-fixed, paraffin-embedded materials, polymerase chain reaction revealed Y. ent. in both cases. Histologically, the epithelioid cell granulomas (EPGs) were transmural in both cases. The EPGs were predominantly nonsuppurative, and were surrounded by a lymphoid cuff composed of small lymphocytes. A portion of EPGs contained suppuration of the centers of the granulomas (central microabscesses). The EPGs were composed of numerous histiocytes with or without epithelioid cell features, along with scattered small T-lymphocytes and plasmacytoid monocytes. None of the EPGs contained monocytoid B-cells. Immunohistochemical study demonstrated that EPGs were usually surrounded by surface IgM/D+ small mantle zone lymphocytes. Moreover, CNA.42 immunostaining occasionally demonstrated residual follicular dendritic cells in the center of the EPGs. The overall histomorphologic and immunohistochemical findings demonstrated that the EPGs with Y. ent. are of the B-cell negative hypersensitivity type and occur in reactive germinal centers. In one case, regional lymph nodes contained EPGs showing the same histologic and immunohistologic findings as those of the appendix. The present study indicates that among abscesses forming epithelioid granulomatous lesions, EPGs with Y. ent. were B-cell negative granulomas, and it demonstrates histopathologic and immunohistochemical findings different from those of cat scratch disease and lymphogranuloma venerum, which contain numerous monocytoid B-cells.     

More newly formed T than B lymphocytes leave the intestinal mucosa via lymphatics

Many lymphocytes are produced in the intestinal mucosa, especially in the Peyer's patches. These newly formed lymphoid cells leave the gut wall, undergo further maturation and many reach the lamina propria of the intestinal mucosa where they function as effector and regulator cells of the intestinal immune response. However, the number and subset composition of these wall are not known. Therefore, the intestinal lymph duct was cannulated in eight minipigs, in which the mesenteric lymph nodes had been removed 3 months earlier. Thus, it was possible to obtain all lymphocytes leaving the intestinal mucosa including the Peyer's patches via lymphatics. The hourly output of lymphocyte subsets was examined over the course of 93 h. The percentage and the absolute numbers of newly formed T cells (CD2⁺, CD8⁺) and B cells (IgA⁺, IgM⁺) were determined by examining the incorporation of the DNA precursor bromodeoxyuridine. After a single i.v. bromodeoxyuridine injection 8.5% of the T, 55% of the IgA⁺ and 25% of the IgM⁺ cells were labeled. In absolute numbers (1.9 ± 0.7) × 10⁶ newly formed T cells, (0.4 ± 0.3) × 10⁶ IgA⁺ cells and (0.5 ± 0.4) × 10⁶ IgM⁺ cells emigrated from the gut wall per hour. Both T and B lymphocyte subpopulations that are produced in the intestinal mucosa leave the gut wall via lymphatics; interestingly, the T cells outnumber the B cells. Obviously the induction and maintenance of mucosal immunity depend to a large extent on the function of newly formed T lymphocytes emigrating from the Peyer's patches and/or from the mucosa without Peyer's patches.     

Kinetic study of mast-cell growth factor production by lymphocytes during the course of Strongyloides ratti infection in mice

Mast-cell growth factor (MCGF) activity in the media conditioned by mesenteric lymph node or spleen cells from Strongyloides ratti-infected C57BL/6 mice was examined by using factor-dependent cell line FDC-P2 or bone marrowderived, cultured mast cells (BMMC) as indicators. Mesenteric lymph node cells from infected mice spontaneously released MCGF activity by culturing for 24 h, showing peak production on days 5–7. MCGF production by mesenteric lymph node cells was augumented after stimulation with adult worm antigen or with concanavalin A (con A). The peak of MCGF production by antigen-stimulated lymph node cells was observed on days 5–7 and declined thereafter. MCGF production by antigen-stimulated spleen cells was lower than that by lymph node cells and reached a peak on day 7 or later. Normal lymph node or spleen cells did not produce MCGF activity even after stimulation with adult worm antigen. The peak of MCGF production by mesenteric lymph node cells preceded the peak of intestinal mastocytosis at the infected site by 4–6 days. The cells producing MCGF had a phenotype of Thy-1⁺, L3T4⁺, and Lyt-2^–. The possible importance of mucosal mast cells in worm expulsion is discussed.     

Cellular composition of suppurative granulomas: an immunohistochemical study of suppurative granulomatous lymphadenitis

The immunohistochemical findings from an investigation of suppurative granulomatous lymphadenitis (SGL) are presented. With a broad panel of monoclonal and polyclonal antibodies directed against B cells, T cells, monocytes/macrophages, HLA-DR antigens, and the transferrin receptor, early, nonsuppurative granulomas were found to consist of OKM1+ OKIa1+ OKT9+ epithelioid histiocytes and multinucleated giant cells, admixed with variable numbers of OKT4+ Leu-3a+ helper/inducer T cells. These nonsuppurative lesions were surrounded by distinctive cuffs of BA1+ B1+ sIgM+ sIgD+ OKIa1+ lymphocytes. In contrast, suppurative granulomas were bordered by palisades of OKM1+ OKIa1+ OKT9+ epithelioid histiocytes, admixed with some OKT8+ suppressor/cytotoxic T cells. These suppurative lesions lacked distinctive cuffs of B lymphocytes, but half of the lesions were surrounded by numerous plasma cells that expressed cytoplasmic IgA and IgG. Based on these immunohistochemical findings, it is concluded that a shift in the nature of the predominant intragranulomatous T-cell subset occurs during the successive phases of the immune response in SGL. The cause of the central necrosis and suppuration may be related to the excessive numbers of intragranulomatous OKT8+ T cells or to the formation of immune complexes by the surrounding plasma cells.     

Janus kinase 3-deficient T lymphocytes have an intrinsic defect in CCR7-mediated homing to peripheral lymphoid organs

Chemokine-mediated signalling involves the activation of a Janus kinase (Jak) pathway. We have previously shown that Jak3 mediates CCR9 and CXCR4 signalling in response to CCL25 and CXCL12 in BM progenitors and thymocytes. The lack of peripheral lymph nodes and Peyer''s patches observed in Jak3^–/– mice suggested a possible role of Jak3 in CCR7-mediated homing to these organs. Here, we demonstrate phosphorylation of Jak3 in peripheral lymphocytes in response CCL19 and CCL21. In addition, Jak3^–/– naïve T cells and pharmacologically inhibited Jak3^+/+ T lymphocytes have impaired chemotactic responses towards these ligands. Interestingly, CCR7 expression was higher in Jak3^–/– thymocytes compared to their Jak3^+/– littermates, indicating that the impaired migration must be caused by impaired CCR7-mediated signalling, in the absence of Jak3. In addition, adoptive transfer experiments showed that Jak3^+/+ mice reconstituted with Jak3^–/– green fluorescent protein (GFP)⁺ bone marrow progenitors had reduced T-lymphocyte homing to peripheral and mesenteric lymph nodes, compared to reconstitution with Jak3^+/+ GFP⁺ progenitors. Furthermore, reciprocal transfer experiments indicated that Jak3^–/– stromal cells were not responsible for the deficient T-cell homing. Finally, we performed direct competitive homing assays and demonstrated that Jak3^–/– T lymphocytes have a clear defect in homing to peripheral and mesenteric lymph nodes, while migration to spleen was moderately impaired. Our data demonstrates that Jak3^–/– T lymphocytes have an intrinsic defect in CCR7-mediated homing to peripheral lymphoid organs.     

Monoclonal antibodies against HLA-DR antigens acting on stimulator cells prevent OKT8+ T lymphocytes from acquiring sensitivity to interleukin 2 and expressing suppressor function

Purified OKT8⁺ but not OKT4⁺ T lymphocytes generated suppressor activity in autologous mixed lymphocyte reactions (AMLR) in the presence but not in the absence of interleukin 2 (IL 2) as determined in proliferative responses of peripheral blood mononuclear cells induced by Concanavalin A, the OKT3 monoclonal antibody and allogeneic cells (indicator systems for suppressor activity used in this study). Furthermore, treatment of AMLR-activated T cells with the OKT8 antibody plus complement abolished suppressor cell activity whereas treatment of the cells with the OKT4 antibody plus complement did not. The three monoclonal anti-HLA-DR antibodies used in this study abrogated the induction, but not the effector phase, of suppressor cells in AMLR. The anti-DR antibodies acted specifically on the stimulator non-T cells and not on the responder T cells. The addition of IL2 to AMLR cultures performed in the presence of the anti-DR antibodies did not restore or increase the suppressor activity whereas IL2 added to AMLR cultures exposed to control antibodies or medium alone increased the suppressor activity. Moreover, purified OKT8⁺ T cells cocultured with autologous non-T cells and IL2, in the presence of the anti-DR antibodies, neither responded to IL2 by proliferating nor expressed suppressor function. In contrast, OKT8⁺ T cells from similar cultures, but performed in the absence of the anti-DR antibodies or exposed to control antibodies, proliferated to IL2 stimulation and exhibited suppressor activity. Unactivated OKT8⁺ T cells were unresponsive to IL2 and unable to express suppressor function. Finally, the addition of the OKT8 antibody (in the absence of complement) to AMLR cultures had no effect on the generation of suppressor cells. From these results, we conclude the following: (a) OKT8⁺ T lymphocytes become sensitive to IL2 by interacting with HLA-DR antigens on the stimulator non-T cells and, with the help of IL2, they express suppressor cell activity; (b) the OKT8 antigenic determinant on AMLR-activated suppressor cells does not seem to participate in their process of activation; (c) results of previous studies showing that OKT4⁺ T lymphocytes become sensitive to IL1 and are capable of synthesizing IL2 after interaction with HLA-DR on the stimulator cells, and the findings presented here, lead us to suggest that both OKT4⁺ and OKT8⁺ T lymphocytes possess receptors for self HLA-DR antigens and that neither the OKT8 nor the OKT4 antigenic determinants on these cells are involved in the recognition of HLA-DR antigens. The suppressor activity generated in AMLR may be one mechanism whereby effector self-tolerance is maintained in the face of inductive self-recognition.     

The In Vitro Effect of a Calf Thymus Extract (Thymostimulin) on T Cell Phenotypes in Cord Blood Lymphocytes

ABSTRACT: An investigation was carried out on the in vitro effect of a calf thymus extract, thymostimulin, on the distribution of T cell phenotypes as defined by OKT3, OKT4, and OKT8 murine monoclonal antibodies and on E-rosetting cells in human cord blood lymphocytes from healthy newborns. The percentages of E-rosette-forming lymphocytes and OKT3⁺ total T population were lower in newborns than in adults (E-rosettes: 43.8% ± 13% vs 57.9% ± 7.9%, p < 0.01; OKT3⁺ cells: 53.3% ± 15.5% vs 79.9% ± 4.7%, p < 0.01), while the OKT4⁺/OKT8⁺ (helper/suppressor) cell ratio was normal in both (newborns: 3.40; adults: 2.44—NS). Thymostimulin increased the number of E-rosette-forming cells from 43.8% ± 13% to 49.9% ± 12.7% (p < 0.01), as well as the percentage of phenotypic T lymphocytes. The highest increases were observed in the OKT4⁺ cells (37.7% ± 14% to 49.1% ± 13.8%, p < 0.001), while smaller changes were observed in the OKT3⁺ cells (53.3% ± 15.5% to 58.1% ± 13.3%, p < 0.02) and OKT8⁺ cells (12.8% ± 6.4% to 16.6% ± 6.5%, p < 0.02). The results of the present study suggest that thymostimulin mainly provokes an increase in the helper T cell phenotype in cord blood lymphocytes.     

Dynamics of Mononuclear Phagocytes in Lymph Nodes and Granulomas in Chronic Tuberculous Inflammation

Quantitative changes in mononuclear phagocytes in lymph nodes and tuberculous granulomas in patients with generalized tuberculosis suggest that accumulation of these cells in granulomas occurs due to their recruiting from bone marrow precursors, rather than from lymph nodes. Antimycobacterial therapy leads to dissociation of granulomas accompanied by accumulation of macrophages in lymph nodes. The number of granulomas decreases, but not their size and relative content of epithelioid cells remain unchanged. With due regard of the microanatomy of granulomas, epithelioid cells are regarded as the main site of mycobacterium persistence and the object of targeted drug delivery.     

Selective labeling of mesenteric lymph nodes: Cell production and emigration ofnewly formed lymphocytes to other organs

Lymphocyte production by mesenteric lymph nodes of normal young pigs was studied by intranodal injections of either tritiated thymidine or tritiated deoxycytidine as DNA precursors. One or two days after selective labeling of the mesenteric lymph nodes the relative and absolute number of lymphocytes derived from mesenteric lymph nodes were determined autoradiographically in the following organs: mesenteric, cervical and inguinal lymph nodes, spleen, thymus, bone marrow, peyer'spatches, tonsil, different regions of the gut, lung and liver. The overall cell production of mesenteric lymph nodes, as derived from the sum of all labeled cells one day after labeling, was estimated to be about 7 × 10⁹ lymphocytes. Up to 40% of all newly formed lymphocytes had already left the lymph nodes within one day and were found in all organs studied. There was a preferential homing to the mucosa of the small intestine, but a considerable number migratedto the spleen and even to the thymus and bone marrow. In lymphoid organs all labeled cells were small and medium-sized lymphocytes one and two days after labeling. In cervical lymph nodes, spleen, tonsil and peyer's patches the relative distribution to T and B cell areas was determined. There was an obvious preference of newly formed lymph node cells to home to T cell areas. The differences of labeling between thymidine or deoxycytidine were surprisingly low.     

Lymphocyte subsets recirculate from blood to lymph at different rates in conscious sheep

Lymphocytes migrate and recirculate continuously between blood and lymph. The current study compared the migratory properties of lymphocyte subsets by labelling lymphocyte surface antigens and analysing simultaneous samples of mesenteric lymph, systemic arterial blood and mesenteric venous blood from conscious sheep. The lymphocyte output in lymph averaged 5.33±0.89×10⁶ min^–1 (lymph flow rate of 92±13 l min^–1, lymphocyte count 61.9±10.7×10⁹ l^–1, n=10) and the proportion of cells which carried the CD4 antigen (CD4⁺) was considerably higher in lymph (46±3 %) than in arterial blood (23±2 %; p<0.01, n=9). This increase was paralleled by a small but statistically significant decrease in the percentage of CD4⁺ cells in mesenteric venous blood(20±2 %), as compared with systemic arterial blood (26±2 %; p<0.05, n=6), which is consistent with the hypothesis that CD4⁺ cells migrate out of the blood vessels, and recirculate through the lymphatics, more readily than other lymphocyte subsets.