Paracortical Areas Of Lymph Nodes Research Articles

Pathohistological features of mediastinal lymphoma in domestic cats

The article covers two clinical cases of domestic cats suffering from a mediastinal form of lymphoma and provides their cytological, immunohistochemical, and pathohistological verification. The lymphoma immunophenotyping method using the B-cell markers CD79a and CD3 was used to identify T-cells. The mediastinal type of lymphoma in cats is usually rarely registered and statistically, the number of cases does not exceed 20%, which is consistent with our observations. Shortness of breath, difficulty with swallowing, lack of appetite, cyanotic mucous membranes, lymphadenomegaly of the mediastinal lymph nodes and effusion in the chest cavity were found in the clinically ill cats. An X-ray examination of the chest cavity revealed an increased contrast in the mediastinal area and displacement of the lungs towards the spine. A complete blood count revealed lymphopenia. Cytological smears of the chest cavity transudates revealed mostly monomorphic lymphoblasts with large rounded hyperchromic nuclei and narrow cytoplasm stained in light blue. The karyoplasm was somewhat granular, the nucleoli were visible, and the mitoses were atypical and numerous. The cytological picture in biopsy samples of mediastinal lymph nodes was characterized by a monomorphic population of lymphoblasts with an eccentrically located nucleus and moderately basophilic karyoplasm. The cell cytoplasm was vacuolated in some places, with presence of atypical mitotic figures. Most of the cells had two nuclei. Diffuse tumoral lesions of the chest cavity tissues, focal tumorous lesions of the lung parenchyma, and lymphadenopathy of the mediastinal lymph nodes were found during the autopsy in the first case. The second clinical case demonstrated the massive lymphadenopathy of the mediastinal lymph nodes. Histologically, a diffuse lesion by a monomorphic population of lymphoblasts was revealed in preparations from the soft tissues of the chest wall. The lymphoblasts’ insignificant cytoplasm, with nuclei from round to elliptical shape, infiltrated the chest wall’s soft tissues. It was found immunohistochemically that the blast cells showed reactivity to CD79a, and were mostly negative to CD3. This indicates the development of a large diffuse B-cell lymphoma. The immunohistochemical picture of lymph node necropsies from another cat was somewhat similar. However, it was also characterized by lymphoblasts with eccentrically placed nuclei, increased number of cells with mitotic figures, somewhat intensive CD3 antibodies expression (especially in the paracortical area of lymph nodes), and significant CD79a marker expression.

Immune System Cells in Healthy Ferrets

The ferret has emerged as an excellent animal model to characterize several physiologic and pathologic conditions. The distribution and characterization of different types of immune system cells were studied in healthy ferret tissues. Eight primary antibodies were tested for immunohistochemistry in formalin-fixed tissues: anti-CD3, anti-CD79α, anti-CD20, anti-HLA-DR, anti-lysozyme, anti-CD163, anti-SWC3, and anti-Mac387. The anti-CD3 antibody labeled T cells mainly in interfollicular and paracortical areas of lymph nodes, cortex and thymic medulla, and periarteriolar lymphoid sheaths in the spleen. The anti-CD79α and anti-CD20 antibodies immunolabeled B cells located in lymphoid follicles at lymph nodes, spleen, and Peyer patches. The CD79α and CD20 antibodies also labeled cells with nonlymphoid morphology in atypical B-cell locations. The anti-HLA-DR antibody labeled macrophages, some populations of B and T lymphocytes, and different populations of dendritic cells in lymph nodes, Peyer patches, spleen, and thymus. The anti-lysozyme antibody immunolabeled macrophages in the liver, lymph nodes, spleen, and thymus. The Mac-387, CD163, and SWC3 antibodies did not show any positive reaction in formalin-fixed or frozen tissues. To elucidate the origin of the uncommon CD79α/CD20 positive cells, a double immunohistochemistry was carried out using the anti-HLA-DR + the anti-CD79α, the anti-HLA-DR + the anti-CD20, and the anti-lysozyme + the anti-CD79α antibodies. Double labeling was mainly observed when the anti-HLA-DR + the anti-CD79α antibodies were combined. The immunohistologic characterization and distribution of these immune system cells in healthy ferret tissues should be of value in future comparative studies of diseases in ferrets.

Laminin and Fibronectin Treatment Leads to Generation of Dendritic Cells with Superior Endocytic Capacity

BackgroundSampling the microenvironment at sites of microbial exposure by dendritic cells (DC) and their subsequent interaction with T cells in the paracortical area of lymph nodes are key events for initiating immune responses. Most of our knowledge of such events in human is based on in vitro studies performed in the absence of extracellular matrix (ECM) proteins. ECM in basement membranes and interstitial spaces of different tissues, including lymphoid organs, plays an important role in controlling specific cellular functions such as migration, intracellular signalling and differentiation. The aim of this study was, therefore, to investigate the impact of two abundant ECM components, fibronectin and laminin, on the phenotypical and functional properties of DC and how that might influence DC induced T-cell differentiation.Methodology/Principal FindingsHuman monocyte derived DC were treated with laminin and fibronectin for up to 48 hours and their morphology and phenotype was analyzed using scanning electron microscopy, flow cytometry and real time PCR. The endocytic ability of DC was determined using flow cytometry. Furthermore, co-culture of DC and T cells were established and T cell proliferation and cytokine profile was measured using H3-thymidine incorporation and ELISA respectively. Finally, we assessed formation of DC-T cell conjugates using different cell trackers and flow cytometry. Our data show that in the presence of ECM, DC maintain a ‘more immature’ phenotype and express higher levels of key endocytic receptors, and as a result become significantly better endocytic cells, but still fully able to mature in response to stimulation as evidenced by their superior ability to induce antigen-specific T cell differentiation.ConclusionThese studies underline the importance of including ECM components in in vitro studies investigating DC biology and DC-T cell interaction. Within the context of antigen specific DC induced T cell proliferation, inclusion of ECM proteins could lead to development of more sensitive assays.

CCR7 mediates the migration of Foxp3+ regulatory T cells to the paracortical areas of peripheral lymph nodes through high endothelial venules

Thymus-derived forkhead box p3(+) naturally occurring regulatory T cells (nTreg) are thought to circulate throughout the body to maintain peripheral immunological self-tolerance through interactions with dendritic cells (DCs), resulting in regulation of conventional T cells. However, the chemokine receptors, which are putatively involved in the in vivo migration of nTreg, have not been fully established. Here, we demonstrated that lymph node nTreg preferentially migrated to the paracortical area of lymph nodes after adoptive transfer, where they were observed to make contact frequently with CD8alpha(+) DCs and CD8alpha(-) CD11b(-) DCs. This migration of nTreg to the paracortical areas was impaired severely when cells were prepared from CCR7-deficient mice. However, to some extent, CCR7-independent migration of nTreg in such CCR7-deficient mice was also observed, but this occurred mainly in the medullary high endothelial venules. Taken together, these data provide the evidence that CCR7 mediates nTreg migration to the paracortical areas of lymph nodes under steady-state conditions; however, CCR7-independent migration also takes place in the medulla.

Cell reservoirs in lymph nodes infected with HIV-1 subtype E differ from subtype B: identification by combined in situ polymerase chain reaction and immunohistochemistry

In Thailand, the predominant HIV subtype is E, rather than subtype B as in North America and Europe. Subtype E has the ability to replicate in vitro in Langerhans cells. We hypothesized that this cell type might constitute a reservoir for the HIV virus in infected lymph nodes. We examined lymph nodes from 25 HIV-1 subtype E-infected patients to determine the immunophenotype of HIV-1-infected cells, their numbers and their distribution. The presence of HIV was detected either by in situ reverse transcriptase-polymerase chain reaction or immunoperoxidase. Cell identity was determined by double labelling using alkaline phosphatase-based immunohistochemistry. The majority of HIV-infected cells in the lymph nodes were Langerhans cells (CD1a+S100+) and Langerhans-related dendritic cells (p55+S100+). These cells were located in the paracortical areas of lymph nodes, with a few cells scattered at the edges of germinal centers, but were absent from germinal centers themselves, in contrast to the reported distribution of subtype B virus. In addition, multinucleated giant cells were significantly more common in HIV-infected nodes (64%) compared to controls (4%) (P=0.00002). In conclusion, Langerhans histiocytes and related cells are reservoirs for HIV subtype E in lymph nodes. Disrupting the pathway of infection of Langerhans cells and related cells may be a viable strategy to interfere with transmission of HIV subtype E.

Ｅｐｓｔｅｉｎ‐Ｂａｒｒ ｖｉｒｕｓの感染を伴った組織球性壊死性リンパ節炎（菊池病）の１例

A case of histiocytic necrotizing lymphadenitis (Kikuchi's disease) accompanied by elevation of the serum antibody against Epstein-Barr virus (EBV)-viral capsid antigen is presented. On histopathological and immunohistochemical studies, infiltration of numerous macrophages (CD68+) and T cells (CD45RO+) was seen around the periphery of a necrotic lesion in the paracortical area of lymph nodes, showing a reduced CD 4+/CD 8+ratio. Furthermore, EBV-encoded latent membrane protein (LMP-1) was detected in the lymphocytes of involved lymph nodes. These findings suggest that this case might be related to EBV infection.

Accumulation of MAC387 + macrophages in paracortical areas of lymph nodes in rhesus monkeys acutely infected with simian immunodeficiency virus

We investigated the histological features of lymph nodes, focusing on monocytes/macrophages, in rhesus monkeys ( Macaca mulatta) acutely infected with simian immunodeficiency virus (SIV). In monkeys infected with a pathogenic SIV, SIVmac239, MAC387 + newly blood-derived macrophages markedly increased in number at paracortical areas at 11 to 14 days postinoculation, concomitant with the peak of the primary SIV antigenemia. The MAC387 + macrophages densely gathered around high endothelial venules and formed cell clusters with CD3 + T lymphocytes, tingible body macrophages, and plasmacytoid monocytes. In the cell clusters, CD3 + T lymphocytes which closely adhered to the MAC387 + macrophages enlarged in size, suggesting a histological manifestation of T-lymphocyte activation by macrophages. By 54 days postinoculation, when SIV antigenemia became undetectable, the MAC387 + macrophages decreased in number and the cell cluster disappeared from paracortical areas. In contrast, the monkeys infected with a nef-deleted mutant of SIVmac239 showed lower levels of SIV antigenemia and lower numbers of MAC387 + macrophages in paracortical areas than those infected with SIVmac239. These results indicate that MAC387 + macrophages accumulate in paracortical areas for the period of the intense primary SIV antigenemia and may play an important role in activating naive T lymphocytes.

Production and characterization of new monoclonal antibodies that distinguish subsets of mink lymphoid cells.

Several hybridoma clones that produce monoclonal antibodies (MAbs) reacting with subpopulations of mink lymphoid cells were established. Two of the MAbs, MTS-4.3 and MTS-9.3, reacted with relatively small populations of surface immunoglobulin (Ig)-negative (Ig-) lymphocytes. MTS-4.3+ and MTS-9.3+ cells were distributed in the thymic cortex and medulla, paracortical areas of lymph nodes, and periarterial lymphoid sheaths of the spleen, indicating that these MAbs identify T lymphocytes. Another MAb, MTB-5.6, reacted with a large proportion of surface Ig+ lymph node cells, but not with surface Ig- cells. In immunohistochemistry this MAb stained dendritic epithelial cells of thymic cortex, large polygonal cells of thymic medulla, a large proportion of lymphocytes in the mantle zone of lymphoid follicles, dendritic-shaped cells of paracortical area, and some lymphocytes and macrophage-like cells of medullary cords and sinuses of lymph nodes. The expression of the cell-surface antigen reacting with MTB-5.6 on Ig+ lymph node cells was increased after concanavalin A stimulation. These new reagents may be useful to analyze cellular basis of the abnormal immune responses observed in Aleutian mink disease, a classical model of human autoimmune diseases.

Characterization and cloning of a novel glycoprotein expressed by stromal cells in T-dependent areas of peripheral lymphoid tissues.

A novel glycoprotein (gp) expressed by stromal cells of peripheral lymphoid tissue has been characterized immunohistochemically, biochemically, and at the molecular level. This molecule, gp38, was identified with a monoclonal antibody (mAb) (clone 8.1.1) previously shown to react with a subpopulation of thymic epithelium. This mAb generated a reticular labeling pattern in medullary and paracortical areas of lymph nodes and in splenic white pulp. At the ultrastructural level, labeling by the 8.1.1 mAb was restricted to fibroblastic reticular stromal cells. Serial sections of lymph node and spleen labeled with anti-CD3, anti-B220, and 8.1.1 mAbs clearly showed that the 8.1.1+ cells were associated with T cell-dependent areas. In severe combined immunodeficiency (SCID) or Nu/Nu mice, splenic white pulp also exhibited reticular labeling with the 8.1.1 mAb in the absence of detectable numbers of T cells, indicating that the appearance of 8.1.1-reactive stromal cells in discrete areas of peripheral lymphoid tissue was T cell independent. The cDNA encoding this stromal cell molecule was cloned by direct expression in COS cells and found to encode a 172 amino acid sequence with the typical features of a type I integral membrane protein. COS cells transfected with the gp38 clone direct the expression of an approximately 38-kD protein that reacts with the 8.1.1 mAb but not with isotype-matched controls. Comparison of the predicted amino acid sequence of 8.1.1 mAb but not with isotype-matched controls. Comparison of the predicted amino acid sequence of 8.1.1 with proteins in the National Biomedical Research Foundation (NBRF) data base showed that gp38 is very closely related to the early response protein OTS-8 obtained from a cDNA library of tumor promoting agent (TPA)-induced murine osteoblastic cell line, MC3T3-E1.

The athymic nude rat Immunobiological characteristics with special reference to establishment of non‐antigen‐specific T‐cell reactivity and induction of antigen‐specific immunity

The aim of the present review has been to describe some immunobiological characteristics of the athymic nude rat and on the basis of these to describe the possibilities of establishing non-antigen-specific T-cell reactivity and inducing antigen-specific immunity. After a brief introduction, some general characteristics of the autosomal recessive rnu/rnu rat are outlined. This athymic mutant normally has a longer lifespan than athymic nude mice and is easier to breed. Inbred nude rats are now available with several rat strain backgrounds. Since the rnu/rnu rat is athymic, the morphology and function of the thymus are briefly described. The thymus has two main functions: production of T lymphocytes and production of thymic hormones. The intrathymic T-cell ontogeny is described along with the two thymocyte selection mechanisms, positive and negative selection. Different thymic hormones are mentioned and their possible function outlined. However, thymic hormones still do not play an important role in immunotherapy. There are some striking differences in the morphology of lymphatic tissues of athymic and euthymic rats. The thymic area in nude rats consists only of fat and clusters of epithelial cells. Little research has been performed on bone marrow of athymic nude rats but morphologically there seems to be no difference from findings in normal animals. The thymus-dependent areas of peripheral lymphoid organs, i.e. the paracortical area of lymph nodes, the periarteriolar sheet of the splenic white pulp, and the interfollicular areas of Peyer's patches, are severely cell-depleted in the athymic nude rat. The lower lymphocyte content of these organs is not reflected in the lymphocyte counts of peripheral blood, but the lymphocyte counts of thoracic duct lymph are much lower than those found in euthymic animals. Few T-lymphocyte marker-positive cells are found in the athymic nude rat, and in the epithelium of the intestine there are also lymphocytes bearing neither T nor B markers. These cells probably represent the tau delta receptor-bearing cells. Immunologically the athymic nude rat reflects the thymic aplasia. Normal B-lymphocyte function has been found in both in vitro and in vivo tests, whereas the T-cell function is virtually absent both in vitro and in vivo. Non-MHC-restricted cells with killer activity like NK cells are present in the nude rat, and these cells function normally both in vitro and in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistopathogenesis of persistent generalized lymphadenopathy in HIV-positive patients

Persistent generalized lymphadenopathy (PGL) is a reactive lymphadenitis affecting HIV-positive patients; furthermore, PGL is often a prodrome of AIDS-related complex and AIDS. In the present review the authors describe the histology and the immunohistochemistry of lymph nodes of patients affected by PGL. Histologic alterations of lymph nodes with PGL are classified according to three main types: follicular hyperplasia without or with follicular fragmentation, follicular involution and follicular depletion. Immunohistology demonstrates a peculiar infiltration of CD3+/CD4+ and CD3+/CD8+ lymphocytes in germinal centers; CD3+/CD8+ are often grouped in small clusters centered by a newly formed small blood vessel. Accessory follicular dendritic reticulum cells (FDRCs) of germinal centers are characterized by a positive staining for p24 and p19 HIV major core antigens. In germinal centers, FDRCs undergo progressive lysis in follicular involution and in follicular depletion. Other viral antigens, such as EBV, are infrequently seen in lymph nodes from HIV-positive patients. Paracortical areas of lymph nodes are often characterized by prominent postcapillary venule proliferations and by hyperplasia of the endothelial cells which are HLA-DR positive, often p19 and p24 positive, and occasionally express HIV genome. In conclusion, in PGL the histologic changes correlate well with the immunohistologic features; accordingly, PGL might be considered the result of abnormal immune reactions to several stimuli still incompletely known.

Double Immunoenzymatic Detection of Surface Phenotype of Proliferating Lymphocytes In Situ with Monoclonal Antibodies Against DNA Polymerase α and Lymphocyte Membrane Antigens

To detect the proliferating cells in situ, a monoclonal antibody against human DNA polymerase alpha (pol alpha) was employed because this enzyme is known to be present in the nucleus of the cells in G1, S, and G2 phases. In addition, the surface phenotype of pol alpha-positive proliferating lymphocytes in diseased lymph nodes was determined by double staining consisting of immunoperoxidase and immunoalkaline phosphatase methods with various monoclonal antibodies against lymphocyte membrane antigens. In the paracortical area of lymph nodes with reactive changes, proliferating cells were 17% or less, and most of them were helper T-cells, although suppressor T-cells and B-cells also proliferate to a certain extent. In contrast, the proliferating cell population in malignant lymphomas was generally more than 40%, and it showed a single surface phenotype, indicating monoclonal proliferation. In addition, an unusual T-cell antigen phenotype of proliferating cells was observed in some cases of peripheral T-cell lymphomas. Thus, this double staining provided the authors with valuable information regarding the proportion, localization, and surface phenotype of proliferating cells, which should be useful for diagnosis of the diseases of lymphoid system.

Increased Langerhans cells and related cells in mesenteric lymph nodes of DNCB-sensitive mice.

We used electron microscopy to study mesenteric lymph nodes (LNs) of 2,4-dinitro-1-chlorobenzene(DNCB)-sensitive mice. It was found that Langerhans cells (LCs) and cells containing Birbeck-granule-like structures (BgSs) increased in number only after challenge with DNCB. This increase reached a peak 4 h after challenge. LCs and BgS cells were only found in the paracortical area of LNs. There were no appreciable differences in the morphology of LCs, BgS cells, and interdigitating reticulum cells (IDCs), except for the presence or absence of Bgs or BgSs. No LCs, BgS cells, or IDCs were found in the marginal sinus of mesenteric LNs or in the surroundings of afferent blood vessels. These findings were in complete agreement with those obtained in our previous study of cutaneous LNs. From our findings and the results of previously published studies, we propose the following conclusions: first, LCs and BgS cells observed in mesenteric LNs are the product of the differentiation and maturation of precursor cells pre-existing in the paracortical area of LNs caused by DNCB stimulation. Second, the activated T lymphocyte to DNCB pre-exists in the paracortical area; thus, the DNCB used for challenge stimulates this T lymphocyte to release lymphokine, which then causes some precursor cells to differentiation into LCs and/or BgS cells. Finally, morphological findings suggest that precursor cells of LCs and BgS cells are probably IDCs.

The location of primary replication of the herpesvirus of bovine malignant catarrhal fever in rabbits

The herpesvirus of malignant catarrhal fever (MCFV) was isolated from the spleen of 2 3 rabbits 4 days after the intravenous inoculation of infectious lymph node suspension, while no virus could be isolated at 2 and 6 days post inoculation (p.i.). Indirect immunofluorescence identified the antigen-positive cells at 4 days p.i. as medium sized lymphocytes lying in the venous sinuses of the spleen, lower numbers of fluorescing cells being seen in the paracortical areas of lymph nodes and in the thymus. Scanty fluorescence, without isolation of virus, was evident in the spleen at 6 days p.i. but by day 8 p.i. virus could be isolated irregularly from spleen and lymph nodes and at 12 days p.i. was found in all lymphoid tissues in those rabbits with lymphadenitis and pyrexia. The primary replication in the spleen at 4 days is compared with other herpes induced lymphoproliferative disorders.

Acute experimental canine ehrlichiosis. I. Sequential reaction of the hemic and lymphoreticular systems.

Dogs with acute Ehrlichia canis infection showed the established clinical features of acute ehrlichiosis and had thrombocytopenia, anemia, increased serum glutamic pyruvic transaminase activity, and decreased total serum protein and albumin concentrations during the first weeks after infection, and increasing gamma globulin concentrations after the third week. Gross lesions in hemic and lymphoreticular tissues were transient lymphadenomegaly, splenomegaly, and increased red long-bone marrow. Lymphoreticular hyperplasia in the paracortical area of lymph nodes and in the splenic red pulp occurred during the second week of infection. Later, small lymphocytes were replaced by medium-sized lymphocytes and plasma cells. Activity of germinal centers increased initially, as shown by numerous mitotic figures and macrophages, but diminished later, and the follicles blended with interfollicular and paracortical tissue because of a decrease in small lymphocytes in the mantle layer. We saw splenic hemorrhages near the perifollicular sinus, and vasculitis, most often phlebitis, in the kidney between weeks 2 and 4. Multifocal reticuloendothelial hyperplasia occurred in the liver during the early stage and injured adjacent hepatocytes by compression. Lesions typical of ehrlichiosis in these dogs were interstitial pneumonia, subendothelial aggregates of mononuclear cells in pulmonary blood vessels, renal periglomerular and perivenular plasmacytosis, hemopoietic hyperplasia, and perivascular cuffs of lymphocytes and plasma cells in many organs.

Immunofluorescence analysis of normal and malignant lymphoid tissues with selected combination of antisera.

Tissue sections stained with combinations of antisera labeled with different fluorochromes (i.e., conventional antisera to human immunoglobulin classes, T lymphocyte antigens, and Ia-like p28,33 antigens used in various double combinations with each other or with different mouse monoclonal antibodies) allow the identification of the different areas of lymph nodes in serial sections and provide great flexibility as well as precision in the analysis of the distribution and relationship of normal and malignant cells. Lymphoid microenvironments in the thymus and the paracortical areas of lymph nodes are described. The close association of T lymphocytes and nonlymphoid cells expressing large amounts of Ia-like antigens (such as interdigitating reticular cells and endothelium) may be relevant for the understanding of immunoregulatory disorders such as dermatopathic and angioimmunoblastic lymphadenopathies and some malignancies (e.g., mycosis fungoides) were the expression of Ia-like antigens on non-T cells seems to be abnormally abundant. The analysis of immunoglobulin and membrane marker expression of normal and malignant B cells and their relation to T cells can also be related to the histology of the disease. These studies are clinically useful for the classification of childhood lymphomas, the differential diagnosis of anaplastic carcinomas and lymphomas, and in the study of the early stages of lymphomas.

Perturbation of Lymphocyte Circulation in Experimental Murine Leprosy

Abstract Infection of Lewis rats with Mycobacterium lepraemurium is characterized by granulomatous pathology primarily involving the paracortical areas of lymph nodes and periarteriolar lymphocyte sheaths of the splenic white pulp. Intravenous infusion of radiolabeled thoracic duct lymphocytes (TDL)2 from normal syngeneic donors failed to produce a significant increase of cell output and radioactivity in the thoracic duct lymph of infected rats as compared with a marked increase in matched control recipients. Conversely, the migration of TDL from infected donor rats was normal in uninfected control rats that had been infused with serum from infected donors. The onset of the lymphocyte traffic disturbance takes place between 2 and 6 weeks after inoculation of viable M. lepraemurium. However, inoculation of heat-killed organisms produces little perturbation of lymphocyte circulation. Thus, the abnormal circulation of TDL in rats with active infection appears to be secondary to granulomatous pathology in lymphoid organs that disturbs cell traffic through these organs.

Perturbation of Lymphocyte Circulation in Experimental Murine Leprosy

Abstract Intravenous infusion of radiolabeled thoracic duct lymphocytes (TDL)2 from normal syngeneic donors to rats experimentally infected with Mycobacterium lepraemurium fails to produce a significant increase of cell output and radioactivity within the thoracic duct lymph. Conversely, there is a marked increase in cell counts and radioactivity in the thoracic duct lymph of control recipients. Splenectomy of infected rats prior to the infusion significantly increased the output of cells and radioactivity from the TD of these rats although it was not restored to normal. Serial quantitation of radioactivity in lymphoid organs of infected rats after infusion of 51Cr-labeled TDL revealed significantly increased uptake by the spleen as compared with the spleens of controls. Thus, the spleen of infected rats was a major trap for recirculating TDL. TDL were also trapped to a lesser extent by the lymph nodes and liver of infected rats. The circulation of TDL was not disturbed significantly in control rats with massive splenomegaly and red pulp hyperactivity induced by i.p. injection of methyl cellulose. Since murine leprosy preferentially involves the periarteriolar lymphocyte sheaths of the splenic white pulp and paracortical area of lymph nodes, it is suggested that the disturbance of lymphocyte circulation is secondary to pathology within these areas.

Studies on the Composition of Adjuvants Which Selectively Enhance Delayed-Type Hypersensitivity to Lipid Conjugated Protein Antigens

Hen egg albumin (HEA), heavily conjugated with dodecanoic acid (D-HEA), stimulated sustained delayed type hypersensitivity (DTH) specific for HEA without detectable antibody formation in guinea pigs. An oil-in-water emulsion containing purified BCG cell walls attached to the oil drops was found to be a very effective adjuvant for enhancing DTH to D-HEA, but not to HEA. Animals immunized with D-HEA in the BCG cell wall emulsion produced skin test reactions 2.4 cm in diameter when challenged with HEA 21 days after a single immunization. Control animals immunized with D-HEA in saline produced skin reactions 1 cm in diameter to similar challenge. Neither group of animals produced detectable antibody to HEA-OR D-HEAmThe emulsion had no adjuvant effect if the BCG cell walls were suspended in the aqueous phase and not attached to the oil droplets. Dodecanoic acid conjugated Salmonella typhi organisms could be used in place of the BCG cell walls to produce effective adjuvant preparations. Fruend's complete adjuvant and other water-in-oil emulsions, however, were found to be ineffective adjuvants for enhancing the degree of DTH produced by D-HEA. Experiments with autoradiography demonstrated that effective adjuvant preparations promote the localization and retention of both 125-I-labeled D-HEA and 125-I-labeled BCG cell walls in the paracortical area of lymph nodes where they are in close proximity to many T-type lymphocytes which proliferate in the induction of DTH.

The Role of Lipid in the Induction of Hapten-Specific Delayed Hypersensitivity and Contact Sensitivity

Abstract Guinea pigs immunized with bovine serum albumin conjugated with dinitrophenol (BSA-DNP), in Freund's complete adjuvant, produce antibody to the DNP and delayed-type hypersensitivity (DTH) to the BSA. We report that immunization with BSA-DNP doubly conjugated with medium chain fatty acids (L-BSA-DNP) stimulates the production of DTH specific for the hapten DNP with minimal antibody to DNP and no detectable immune response to the carrier BSA. The production of hapten-specific DTH reactions was assessed by two methods. First, animals immunized with L-BSA-DNP produced typical contact sensitivity reactions to epidermal challenge with dinitrofluorobenzene. Second, they produced grossly and microscopically typical delayed hypersensitivity reactions to the intradermal injection of DNP conjugated either to BSA or to a non-cross-reacting carrier, hen egg albumin. In further experiments, DNP-specific DTH was produced by animals immunized with BSA-DNP to which lipid groups had been attached by electrostatic rather than covalent bonds. Evidence is discussed which indicates that the production of DTH to haptens and proteins is largely a function of the lipophilic nature of the entire immunogen and is not dependent upon properties of individual antigenic determinants. Autoradiographic studies with 125I-labeled material demonstrated that the lipid-rich antigens are localized in the paracortical area of lymph nodes, in close proximity to the thymus-derived cells which are stimulated in the induction of DTH.