I. Effect of Trichinella spiralis infection on the migration of mesenteric lymphoblasts and mesenteric T lymphoblasts in syngeneic mice.

The migration of [125I]UdR-labelled mesenteric lymph node cells in NIH strain mice at various times after inis produced an enhanced accumulation of mesenteric immunoblasts in the small intestine at 2 and 4 days after infection but not at later times. The enhanced migration occurred when using cells from both uninfected and infected donors, denoting an absence of antigenic specificity. This effect is not secondary to a reduced arrival of cells at sites away from the gut in infected mice, but to a primary increase of the arrival in the small intestine. Mesenteric T lymphoblasts (separated on a nylon-wool column) migrated to the small intestine of uninfected recipients and appear to be a major portion of the population which migrate to the gut of infected recipients. Our results were confirmed using 51Cr to label mesenteric cells. We conclude that the parasite causes the small intestine to become more attractive or retentive for mesenteric blast cells early during infection.     

The reduction of worm burden and egg production inMicrophallus pygmaeus (Levinsen 1881) (Digenea: Microphallidae) induced by a concurrent infection withHymenolepis nana (Cestoda: Cyclophyllidea)

Male and female albino mice, with an existing natural infection of the cestode,Hymenolepis nana harbour significantly fewer experimentally infectedMicrophallus pygmaeus with significantly fewer eggs in their uteri than their counterparts in which the cestode infection had been eliminated by treatment with piperazine citrate.     

Selective migration of lymphocytes within the mouse small intestine

The factors which determine the migration of lymphoid cells to lamina propria or Peyer's patches of mouse small intestine have been investigated by autoradiographic tracing of intravenously injected spleen, thymus and lymph node cells. The numbers of labelled cells found in antigen-free grafts of foetal small intestine were compared with the numbers in normally sited gut. Thymus, normal spleen and B spleen lymphocytes, labelled with [³H]adenosine or [5-³H]uridine, were confined to Peyer's patches in normal and grafted gut. [³H]Thymidine-labelled lymphoblasts from the mesenteric nodes of young (19–22 days) mice and mice infected with Nippostrongylus brasiliensis were found in the lamina propria of both graft and normal small intestine, but [³H]thymidine-labelled lymphoblasts from oxazolone-primed lymph nodes did not migrate to the villi. The possible roles of intraluminal antigens, source of cells and changes in cell surface receptors during differentiation, in determining the selective migration of cells to the lamina propria and Peyer's patches, are discussed.     

The in-vivo kinetics of lymphoblast localization in the small intestine.

We have studied the in-vivo kinetics of the accumulation of 125I-UdR labelled mesenteric lymphoblasts in the small intestine of mice. The efficiency with which the labelled cells were extracted from the blood and retained by the intestine was quantified by examination of the accumulations observed over the first 4 hr after cell transfer. The kinetic parameters for the uptake and retention of lymphoblasts determined from these early times were found to provide a good approximation to the entire time course of accumulation observed from 1 hr to 22 hr after cell transfer. For normal mice, approximately 1% of lymphoblasts delivered by the blood stream at any given time gained entry to the small intestine and were retained with an average half-time of 6.5 hr. We also studied the accumulation of lymphoblasts in the small intestine of mice undergoing a self-limited enteric infection with the nematode, Trichinella spiralis. There was a greater accumulation of lymphoblasts in the small intestine of these animals. This was the consequence of a prolongation of the half-time for retention of lymphoblasts within the intestine to 15 hr, rather than increased uptake of lymphoblasts from the blood. During a secondary infection with T. spiralis, the half-time for retention of lymphoblasts in the intestine was decreased to 3 hr. These studies show that viewing the accumulation of lymphoblasts as the result of a series of first order kinetic processes provides a suitable model for the migration of lymphoblasts to the small intestine.     

Hatching requirements of dwarf tapeworm eggs (Hymenolepis nana) in relation to extraintestinal development of larval stages in mice

Summary It was established that cracked eggs of Hymenolepis nana would develop in the usual manner to the cysticercoid stage within 5 days when injected subcutaneously or intramuscularly into previously uninfected mice. Intestinal enzymes were not necessary to hatching stimulation. The majority of cysticercoids which developed subcutaneously in normal mice survived 3 weeks, relatively few survived 5 weeks, and there was some evidence that several may have survived as long as 8 weeks after infection. Due to the potential for extraintestinal development and survival exhibited by H. nana larval stages, it was suggested that this factor must be considered when attempting to explain the characteristically high level of infection immunity apparent with this parasite.

---

Zusammenfassung Es wurde festgestellt, daß sich die Embryonen gesprengter Eier von Hymenolepis nana innerhalb von 5 Tagen in üblicher Weise zu Cysticercoiden entwickeln, wenn sie subkutan oder intramuskulär in sicher nichtinfizierte Mäuse injiziert werden. Intestinale Enzyme dürften danach also nicht zur Stimulation des Schlupfvorganges erforderlich sein. Die meisten dieser Cysticercoide überlebten 3 Wochen, relativ wenige auch 5 Wochen, einige sogar 8 Wochen. Im Hinblick auf die Fähigkeit zur extraintestinalen Entwicklung und die festgestellte Überlebenszeit wird angenommen, daß dieser Faktor berücksichtigt werden muß, wenn man den charakteristischen hohen Grad von Immunität, durch den dieser Parasit bekannt ist, zu erklären versuchen will.

     

Human and mouse perforin are processed in part through cleavage by the lysosomal cysteine proteinase cathepsin L

Summary Infection of mice with the gastrointestinal nematode Trichuris muris represents a valuable tool to investigate and dissect intestinal immune responses. Resistant mouse strains respond to T. muris infection by mounting a T helper type 2 response. Previous results have shown that CD4⁺ T cells play a critical role in protective immunity, and that CD4⁺ T cells localize to the infected large intestinal mucosa to confer protection. Further, transfer of CD4⁺ T cells from immune mice to immunodeficient SCID mice can prevent the development of a chronic infection. In the current study, we characterize the protective CD4⁺ T cells, describe their chemokine receptor expression and explore the functional significance of these receptors in recruitment to the large intestinal mucosa post‐T. muris infection. We show that the ability to mediate expulsion resides within a subpopulation of CD4⁺ T cells marked by down‐regulation of CD62L. These cells can be isolated from intestine‐draining mesenteric lymph nodes (MLN) from day 14 post‐infection, but are rare or absent in MLN before this and in spleen at all times post‐infection. Among CD4⁺ CD62L^low MLN cells, the two most abundantly expressed chemokine receptors were CCR6 and CXCR3. We demonstrate for the first time that CD4⁺ CD62L^low T‐cell migration to the large intestinal mucosa is dependent on the family of Gα_i‐coupled receptors, to which chemokine receptors belong. CCR6 and CXCR3 were however dispensable for this process because neutralization of CCR6 and CXCR3 did not prevent CD4⁺ CD62L^low cell migration to the large intestinal mucosa during T. muris infection.     

Kinetics of mast cells,eosinophils and phospholipase B activity in the spontaneous-cure response of two strains of mice (rapid and slow responder) to the cestodeHymenolepis nana

Primary egg-derived infection ofHymenolepis nana (100 eggs) in BALB/c (rapid responder) and C3H (slow responder) mice resulted in increased levels of mucosal mast cells (MMCs), eosinophilia (bone marrow, peripheral, tissue) and phospholipase B activity. The response appeared to be similar in both strains used, with a slight difference in cellular accumulation but a significantly earlier response in BALB/c than in C3H mice. These findings suggest that the prolongation ofH. nana infection in C3H mice may be related to the delayed appearance of MMCs and eosinophils, which triggers a slower generation of the intestinal inflammation response. The rapidity with which phospholipase B activity increased was strictly correlated with eosinophil tissue number; this further supports the hypothesis for a direct parallel between eosinophils and phospholipase B activity in infected tissue.     

Dendritic cells have a crucial role in the production of cytokines in mesenteric lymph nodes of B10.BR mice infected with Trichuris muris

Dendritic cells bridge innate and adaptive immunity and establish protective immunity to pathogens. Protection against the murine nematode parasite Trichuris muris depends on the T helper 2 (Th2) response and requires the Th2 cytokines interleukin 4 (IL-4), IL-10, or IL-13. To examine if the Th2 response to T. muris infection is regulated by CD11c⁺B220⁻ dendritic cells in mesenteric lymph nodes, dendritic cell-enriched and dendritic cell-depleted fractions were obtained from mesenteric lymph node cells of T. muris-infected mice, and production of cytokines in cultures of these fractions was measured. At day 14 postinfection, no worm expulsion was observed, and high levels of interferon γ production occurred in dendritic cell-enriched fractions. Expulsion of worms occurred on days 20 and 25 postinfection, and IL-10 production was induced in dendritic cell-enriched fractions on these 2 days. No cytokine production was observed in mesenteric lymph node cells and dendritic cell-depleted fractions during T. muris infection. The occurrence of worm expulsion was consistent with IL-10 production in dendritic cell-enriched fractions. IL-10 inhibits Th1 cells and promotes the Th2 response, and results from this study suggest that CD11c⁺B220⁻ dendritic cells in the mesenteric lymph nodes are required for IL-10 production and the IL-10-dependent protective Th2 response.     

Dendritic cells in Leishmania major-immune mice harbor persistent parasites and mediate an antigen-specific T cell immune response

Upon infection with Leishmania major, a cause of human cutaneous leishmaniasis, mice of resistant strains are able to control the infection, with lesions resolving spontaneously. A long-lasting cell-mediated immunity protects them from reinfection. Nevertheless, small numbers of viable parasites persist in the lymph nodes of these mice. We have recently documented that, in addition to macrophages, epidermal Langerhans cells can ingest L. major. Furthermore, Langerhans cells have the unique ability to transport viable parasites from the infected skin to the draining lymph node for presentation to antigen-specific T cells and initiation of the cellular immune response. During migration, Langerhans cells develop into dendritic cells. In the present study, we analyzed whether dendritic cells support the persistence of parasites in immune hosts. Immunohistological studies and assays in vitro showed that in the lymph nodes of mice that have recovered from infection with L. major, both macrophages and dendritic cells harbor viable parasites. However, only dendritic cells were able to induce a vigorous T-cell immune response to L. major in vitro in the absence of exogenous antigen. Tracking experiments conducted in vivo suggested that the infected dendritic cells in the lymph nodes are derived from Langerhans cells that have emigrated from the skin. The data demonstrate that L. major-infected dendritic cells and macrophages in lymph nodes of immune animals represent long-term host cells, but only dendritic cells have the ability to present endogenous parasite antigen to T cells. Long-term infected dendritic cells may thus allow the sustained stimulation of a population of parasite-specific T cells, protecting the mice from reinfection. Our results favor the hypothesis that the persistence of antigen supports the maintenance of T cell memory and that dendritic cells are critically involved in this process.     

Immunological memory function of the T and B cell types: distribution over mouse spleen and lymph nodes

Spleens from LAF₁ mice injected intravenously with sheep erythrocytes (SE) are relatively rich in memory T cells early in the immune response (1 to 3 days) and rich in memory B cells as the response progresses (2 weeks or more). Marked cooperation for the secondary immune response in vitro was obtained by combining 10⁶ spleen cells from LAF₁ mice, taken 2 days after intravenous priming with SE, with 10⁷ spleen cells from day 14 primed mice. The results indicate relative deficiencies in the spleen for B memory cells on days 1 to 2 and for T memory cells on day 14 after priming. Day – 14, but not day – 2, immune lymph node (LN) cells could replace the day – 2 spleen cells (anti-Thy 1.2 sensitive) in the in vitro cooperation with day – 14 immune spleen cells. Immune spleen cells taken 4 to 7 days after priming contain more equivalent numbers of B and T memory cells, but 10 to 7 days after transfer of such immune spleen cells without SE into irradiated recipients the T memory cells were again more prominent in lymph node and the B memory cells in spleen as shown by in vitro cooperation studies. These results suggest that during the second week after intravenous injection of SE relatively more T than B memory cells migrate from spleen to lymph node, resulting in an imbalance in the splenic memory cell population favoring B memory cell function.     

Factors which determine the accumulation of immunoblasts in gut and skin

The capacity of immunoblasts from two sources [1] peripheral lymph nodes draining the site of application of a contact sensitizer and [2] mesenteric lymph nodes from mice infected with the gut parasiteT. spiralis to migrate to the gut and to inflamed skin sites were compared.The peripheral lymph node blasts readily entered skin sites in a non-specific way but failed to migrate to the gut even when inflammation was induced. By contrast, the mesenteric lymph node blasts readily migrated to the gut in normal mice and in increased amounts to the gut of mice infected withT. spiralis or inflamed with oral turpentine. A small proportion of mesenteric lymph node blasts did, however, migrate, non-specifically to the skin but in much smaller amounts than peripheral lymph node blasts.We conclude that the migration of immunoblasts to the gut has some specificity related to the source from which the cells were taken but little specificity with regard to intraluminal antigen.     

The 44th Annual Meeting of the Scandinavian Society of Immunology

Hymenolepis nana is the most commonly known intestinal cestode infecting mainly human. This study aimed to investigate the potential effect of chitosan particles (CSP) to enhance the immune system against H. nana infection. Determination of worm burden, egg output, histopathological changes, oxidative stress markers (lipid peroxidation and reduced glutathione), goblet (GCs) and mucosal mast cells (MMCs) counts in intestinal ileum was performed. In addition, levels of intestinal mRNA expression of interleukin (IL)‐4, IL‐9, stem cell factor (SCF), type I and II interferons (IFN)‐α/ γ, tumour necrosis factor (TNF)‐α, mucin 2 (MUC2) and inducible nitric oxide synthase (iNOs) were investigated using real‐time PCR. The results indicated induced reductions in adult worm and egg counts in infected mice after CSP treatment. This was associated with improvement in tissue morphometric measurements and oxidative stress which were altered after infection. Expression levels of iNOs, IFN‐α, IFN‐γ, TNF‐α and IL‐9 were decreased by CSP. Conversely, expression levels of MUC2, IL‐4 and SCF increased compared to infected untreated group. In addition, GCs and MMCs counts were normalized by CSP. In conclusion, this study could indicate the immunoprotective effect of CSP against H. nana infection. This was characterized with Th2 anti‐inflammatory responses.     

Characteristics of Schistosoma japonicum infection induced IFN‐γ and IL‐4 co‐expressing plasticity Th cells

Schistosoma japonicum infection can induce granulomatous inflammation and cause tissue damage in the mouse liver. The cytokine secretion profile of T helper (Th) cells depends on both the nature of the activating stimulus and the local microenvironment (e.g. cytokines and other soluble factors). In the present study, we found an accumulation of large numbers of IFN‐γ⁺ IL‐4⁺ CD4⁺ T cells in mouse livers. This IFN‐γ⁺ IL‐4⁺ cell population increased from 0·68 ± 0·57% in uninfected mice to 7·05 ± 3·0% by week 4 following infection and to 9·6 ± 5·28% by week 6, before decreasing to 6·3 ± 5·9% by week 8 in CD4 T cells. Moreover, IFN‐γ⁺ IL‐4⁺ Th cells were also found in mouse spleen and mesenteric lymph nodes 6 weeks after infection. The majority of the IFN‐γ⁺ IL‐4⁺ Th cells were thought to be related to a state of immune activation, and some were memory T cells. Moreover, we found that these S. japonicum infection‐induced IFN‐γ⁺ IL‐4⁺ cells could express interleukin‐2 (IL‐2), IL‐9, IL‐17 and high IL‐10 levels at 6 weeks after S. japonicum infection. Taken together, our data suggest the existence of a population of IFN‐γ⁺ IL‐4⁺ plasticity effector/memory Th cells following S. japonicum infection in C57BL/6 mice.     

B-cell activation in the mesenteric lymph nodes of resistant BALB/c mice infected with the murine nematode parasite Trichuris muris

Immune responses in resistant BALB/c mice infected with the murine nematode parasite Trichuris muris were examined. Following the establishment of infection, worm burdens of T. muris were expelled by BALB/c mice by day 21 postinfection (p.i.). Specific immunoglobulin G₁ (IgG₁) antibodies to T. muris excretory/secretory (E/S) antigens were detected in sera from infected mice, though specific IgG_2a antibodies were not observed during infection. Ig-producing cells increased in the mesenteric lymph nodes (MLN) of infected mice on days 7, 14, and 21 p.i., with the greatest increase in numbers of IgG- and IgA-producing cells occurring on day 14. Marked increases in the relative percentages of B220⁺ and surface Ig⁺ (sIg⁺) cells were observed in the MLN of infected mice on days 14 and 21 p.i. Furthermore, cellular expansion of the MLN in infected mice resulted in an increase in the absolute numbers of B220⁺ and sIg⁺ cells. The levels of interleukin 2 (IL-2), IL-4, and interferon-γ (IFN-γ) detected in the supernatants from concanavalin A-stimulated MLN cells of infected mice were higher than those found in normal mice. Consequently, the expulsion of T. muris in resistant BALB/c mice was concomitant with cytokine production and B-cell activation in the MLN of infected mice. These results suggest the involvement of B-cell responses in protective immunity to T. muris infection. Received: 12 May 1998 / Accepted: 5 August 1998     

Resistance to ectromelia virus infection in mice Analysis ofH-2-linked gene effects

Summary The mechanism for resistance to ectromelia infection has been investigated in B6 and B10 congenic strains of mice which carry different alleles at theH-2 major histocompatibility locus. Greater susceptibility in some B10 congenic strains of mice has been associated with higher viral titres in the draining popliteal and inguinal lymph nodes as well as spleen at 3 days post infection. T cells which develop cytotoxic function following in vitro culture in the presence of T cell growth factors have also been detected in the popliteal lymph nodes of B6/B10 congenic strains of mice as early as 3 days post infection. Greater cytotoxicity has been detected in cultures of cells from resistant B6/B10 mice than from the susceptible B10 congenic strain B10.G, or other semi-resistant B10 congenic strains which differ at theH-2 locus. The early activation of T cells appears to be underH-2 gene control and activated T cells may play an early role in controlling viral replication within the lymphoid system.     

The cellular transfer of immunity to Trichostrongylus colubriformis in an isogenic strain of guinea-pig: II. The relative susceptibility of the larval and adult stages of the parasite to immunological attack

Cells obtained from mesenteric lymph nodes of highly inbred guinea-pigs (Heston strain) resistant to Trichostrongylus colubriformis were injected into virgin animals of the same genotype. The adoptively immunized recipients were challenged with 1000 T. colubriformis larvae 4 days after transfer and slaughtered at intervals which correspond to critical times in the development of the parasite. Differential worm counts carried out on specimens of intestine showed that a sharp decline in the number of parasites occurred between days 7 and 9. This period corresponds to the time required for the parasite to develop to the fourth larval stage.

Variation of the time interval between cell transfer and challenge showed that immune cells transferred on the day of challenge and on days 4, 6 and 8 after challenge inhibited the development of infection to patency, while cells injected on day 10 were without effect. This observation confirmed that the fourth larval stage of the parasite is uniquely susceptible to the immunological attack initiated by the transferred cells and showed that these cells are effective within 24–48 hours after injection. This latter finding excludes the possibility of active participation in the response by the recipient.

Resistance can be transferred by spleen cells and by cells obtained from lymph nodes other than the mesenteric nodes which drain the site of infection. However the local nodes are more effective and resistance was regularly transferred with as few as 10 × 10⁶ cells injected intravenously.

     

In vivo tracking and protective properties of Yersinia-specific intestinal T cells

After invasion via M cells enteropathogenic Yersinia enterocolitica subsequently establish an infection at three different sites: (i) Peyer's patches (PP), (ii) mesenteric lymph nodes (MLN), and after systemic dissemination in (iii) spleen, liver and lung. In order to characterize protective properties of intestinal T cells at the different sites of Y. enterocolitica infection, PP and MLN T cells were isolated from Y. enterocolitica-infected C57Bl/6 mice and Yersinia-specific T cell lines were generated. These T cells exhibited the phenotype of CD4 Th1 cells. The adoptive transfer of Yersinia-specific Th1 cells from PP and MLN conferred protection against a lethal orogastric inoculum with Y. enterocolitica as revealed by survival post-infection. However, determination of bacterial counts in infected organs revealed that the transfer of PP T cells conferred protection in spleen but not in MLN and PP, whereas the transfer of T cells from MLN reduced bacterial counts in both spleen and MLN but not in PP. To elucidate the different protection pattern we wanted to track the transferred cells in vivo. For this purpose the cells were labelled with the stable green fluorescent cell linker PKH2-GL prior to the adoptive transfer. In vivo tracking of these cells revealed that the distribution pattern of transferred T cells in spleen, MLN and PP correlated closely with the protection pattern observed after Yersinia infection. Thus, most cells were recovered from the spleen, while only few cells were recovered from MLN and PP. In keeping with these results a rapid and significant increase in interferon-gamma (IFN-γ) production in the spleen of mice after adoptive transfer of T cell lines was observed. Taken together, the present results demonstrate that intestinal CD4 Th1 cells from PP and MLN may be involved in the defence against Y. enterocolitica at different sites of the infection, and that PKH2-GL labelling is a suitable tool to characterize T cell functions in vivo.     

Cellular changes in bone marrow of malaria-infected mice

The number of bone marrow cells and their chemotactic activity was studied during malaria infection. Two days after infection of Balb/c mice withPlasmodium berghei, an increase in granulocyte number was observed in the blood. A modified Boyden chamber chemotaxis assay was employed to investigate the mechanism of granulocyte accumulation in the blood. Bone marrow cells from normal mice, from mice during a primary lethal infection and from immune mice after challenge were compared. The complement factor C5a showed chemotactic activity for bone marrow cells; a significant decrease of chemotaxis was only observed after 6 days of primary infection. Extracts of spleen, liver and infected erythrocytes lacked chemotactic activity, or caused inhibition of cell migration. Serum from mice with a 2-day primary infection contained chemotactic activity. The active component was heat labile, protease sensitive and had an estimated molecular weight of 250,000.     

Phenotypic changes in T cell populations during the reactivation of tuberculosis in mice

The phenotypic changes of T lymphocytes during the reactivation of latent Mycobacterium tuberculosis infection by activation of the hypothalamic–pituitary–adrenal (HPA) axis was monitored using flow cytometric analysis. Subsets of CD4⁺ and CD8⁺ lymphocyte populations from the lung, spleen and draining lymph nodes of infected mice were identified based on their differential expression of the cell surface antigens CD44 and CD45RB. Latent infection was characterized by an accumulation of both naive, activated and memory CD4 and CD8 T lymphocytes in the lung and mediastinal lymph nodes. No changes were observed in the spleen of mice with latent infection when compared with uninfected mice. Immediately following the activation of the HPA axis, a reduction in all CD4⁺ and CD8⁺ T cells in the lung and mediastinal lymph nodes was observed. This correlated with the reactivation of mycobacterial growth. The decrease was transient for memory and naive CD4 and CD8 T lymphocyte populations in the lung. However, the number of naive CD4 and CD8 T lymphocyte populations in the mediastinal lymph node following reactivation was less than that found in mice with latent infection. These data provide the first characterization of T lymphocyte populations which may be functionally involved in the immunological response to HPA axis-induced reactivation of M. tuberculosis infection.     

Lactic Dehydrogenase Virus Inhibits Allergic Immunoglobulin E Production: In Vivo Molecular Analysis of Cytokines

The effects of lactic dehydrogenase virus (LDV) infection on allergic immunoglobulin (Ig)E production and interleukin (IL)-4 gene expression were studied. LDV infection suppressed antigen-induced IgE production in sensitized mice. The elevations of IL-4 gene expression in spleen and mesenteric lymph nodes 3 and 7 days after ovalbumin challenge were suppressed significantly in LDV-infected mice compared with control mice. The expression of the interferon (IFN)-gamma gene of mesenteric lymph nodes was significantly increased in LDV-infected mice. These results suggest that LDV infection suppressed antigen-induced IgE production by decreasing IL-4 production, and that suppression of IL-4 gene expression may be mediated by a mutual inhibition mechanism between T helper (Th)1 and Th2 cells.