Influence of resistant and susceptible genotype, IL-1, and lymphoid organ on Trichinella spiralis-induced cytokine secretion

The relative importance of cell-mediated inflammatory responses and antibody-mediated responses in controlling parasitic helminth infection is debated. To study the relationship between these responses and resistance or susceptibility to primary Trichinella spiralis infection, we infected resistant AKR mice and susceptible B10.BR mice and analyzed the lymphokines IL-2, IFN-gamma, and IL-5 produced by their T cells as a function of time and lymphoid organ. IL-2-secretors occurred maximally between days 3 and 6 postinfection, whereas IL-5-secretors peaked between days 6 and 9. Previously, we found that IFN-gamma producers peaked before day 6, whereas IL-4 producers peaked between days 6 and 9. Most cytokine secretors were CD4+. The simultaneous development of IL-2- and IFN-gamma-secreting cells, and IL-4- and IL-5-secreting cells, suggests that the infection may be stimulating T cells to differentiate into cells capable of secreting specific cytokine sets, analogous to the postulated Th1 and Th2 subsets. In the spleen and mesenteric lymph nodes, cells from B10.BR mice secreted more IL-5 than cells from AKR mice, as we found previously for IL-4. For both strains, mesenteric lymph node cells produced more IL-5 than splenocytes. The AKR mesenteric lymph node cells produced more IL-2 than the B10.BR cells, but the reverse occurred in splenocytes. The AKR peripheral lymph node cells also secreted more IFN-gamma than the B10.BR cells, but the strains were equivalent for peritoneal exudate cell IFN-gamma production. Thus, the lymphoid organ microenvironment plays an important role in regulating cytokine-secreting cell development in this system. We also tested the possible regulatory role of IL-1. Exogenous rIL-1 alpha increased IFN-gamma secretion early but not late in mesenteric lymph node cells from both strains; this reflected an increased IFN-gamma-secreting cell frequency, not a change in IFN-gamma mRNA transcript level. Exogenous rIL-1 alpha did not consistently affect IL-2, IL-4, or IL-5 secretion. These data suggest that IL-1 alpha availability in vivo may regulate IFN-gamma-secreting cell development. In sum, early activation of IFN-gamma-secreting T cells in lymph nodes, with little subsequent activation of IL-4- and IL-5-secreting cells, distinguished the resistant from susceptible strain responses to T. spiralis infection, and IL-1 alpha and lymphoid organ environment influence IFN-gamma-secreting cell activation.

Schistosoma mansoni: peritoneal plasmacytogenesis and polypoid transformation of mesenteric milky spots in infected mice

We have studied inflammatory reactions in the mesenteric tissue of mice infected with Schistosoma mansoni. Perivascular tissue contained diffuse infiltrates of macrophages, eosinophilic granulocytes and lymphocytes. Angiogenesis in the perivascular adipose tissue was associated with superficial plasmacytogenic foci. Polypoid structures were occasionally formed adjacent to inflammatory foci in the adipose tissue, organized around loops of capillaries, with terminal formation of a glomerular capillary network embedded in connective tissue, covered by plasmacytes. We conclude that these structures are specialized milky spots dedicated to active plasmacytogenesis and antibody secretion into the peritoneal cavity of schistosome-infected mice.

The in vitro production of cytokines by mucosal lymphocytes immunized by oral administration of keyhole limpet hemocyanin using cholera toxin as an adjuvant

The in vitro production of a variety of cytokines by lymphocytes isolated from spleen mesenteric lymph node (MLN), Peyer's patches (PP) and lamina propria (LP) was measured, after oral immunization with keyhole limpet hemocyanin using cholera toxin as an adjuvant. LP responses were characterized by very high levels of interleukin (IL) 4, IL 5 and IL 6 with lower levels of IL 2 and interferon-gamma (IFN-gamma). The PP had lower levels of IL 4, IL 5 and IL 6 than LP but higher levels of IL 2, IFN-gamma was only present at very low levels in this organ. The MLN had a pattern of cytokine production similar to the PP but did produce IFN-gamma. The spleen produced all cytokines measured except IL 5. Antibody production was characterized by IgA in the LP and PP but IgG was the dominant isotype in the spleen, the MLN was a poor source of antibody-producing cells. We interpret the results to show that (a) the LP response to cholera toxin/keyhole limpet hemocyanin is dominated by Th2-type cytokines compared to a lower production of Th1 type and (b) that the PP has responses typical of an organ with a high proportion of resting lymphocytes which develop mainly into Th2-types cells. The spleen is less dominated by Th2-type cytokines than the mucosal sites and this difference is paralleled by IgA antibody production at the mucosal sites and IgG antibody dominance in the spleen.

Murine intestinal antibody response to heterologous rotavirus infection

Rotavirus is the most important worldwide cause of severe gastroenteritis. Extensive efforts have been devoted to the design of a vaccine that will prevent disease, but development of a more effective vaccine strategy may require progress in the understanding of the mucosal immune response to replicating viral antigens. In this article, we report the characterization of the intestinal antibody response of a murine model to heterologous infection with the rhesus rotavirus vaccine strain. We have adapted the enzyme-linked immunospot assay to measure this response without the difficulties associated with measurement of antibodies in intestinal contents or the artifacts associated with culturing of lymphocytes. The predominant response in terms of antibody-secreting cells (ASC) is seen in the small intestine lamina propria, which can be measured within 4 days of infection, peaks 3 weeks after infection, and remains near that level for longer than 8 weeks. The magnitude of the immunoglobulin A (IgA) cell response is approximately 10 times greater than the intestinal IgG cell response, and IgM cells are rare. Virus-specific ASC constitute approximately 50% of all ASC in the gut at the peak of the virus-specific response. This response is considerably greater than responses to nonreplicating mucosal antigens measured by similar techniques. Enteral infection engenders minimal virus-specific ASC response in the spleen. Rhesus rotavirus-specific enzyme-linked immunosorbent assay and neutralization assays of serum and intestinal contents did not correlate with virus-specific ASC response.

Size, CD4 and CD8 marker profiles and functions of lymphocyte subpopulations in mucosal-associated lymph nodes

We analyzed phenotypic and functional characteristics of T cell populations in mucosal-associated supramammary and mesenteric lymph nodes in goats. Here we demonstrate, by flow cytometry, quantitative differences in CD4 and CD8 T cell subsets among large and small mucosal-associated lymphocyte populations and their differential regulatory activities on resident lymph node B cells stimulated with Staphylococcus aureus Cowan I or pokeweed mitogen. The CD4/CD8 T cell ratio was lower in mesenteric lymph nodes (1.46) when compared to that of supramammary lymph nodes (2.18). Analysis of large and small lymphocyte subpopulations from lymph nodes showed nearly 62% of the lymphocytes from mesenteric lymph nodes being of large cell phenotype with CD4/CD8 ratios of 1.34. In contrast, large cell subpopulations in supramammary lymph nodes showed a significantly lower number (50%) with a higher CD4/CD8 ratio of 2.05. Functionally, mesenteric lymph node T cells, isolated by nylon wool, showed heightened suppressive activity in mitogen-driven B cell proliferation responses, whereas T cells from supramammary lymph nodes were stimulatory. These findings clearly demonstrate distinctive functional properties between resident T cell populations of supramammary and mesenteric lymph nodes, suggesting that different proportions of T cell subsets in these nodes are activated and thus regulate regional immune responses via different pathways.

Kinetics of the in vitro antibody response to transmissible gastroenteritis (TGE) virus from pig mesenteric lymph node cells, using the ELISASPOT and ELISA tests

A method is described for in vitro studies of viral humoral immune responses in the pig. After oral immunization with transmissible gastroenteritis (TGE) coronavirus, antibody production from primed mesenteric lymph node cells was revealed by an in vitro boost with viral antigen. For the latter the leukocytes were co-cultured with UV-inactivated virus using a variety of different methods of antigenic stimulation. Enumeration of specific antibody-secreting cells (ASC) and titration of secreted anti-virus antibodies were performed with ELISASPOT (using 3-amino 9-ethyl carbazole as the peroxidase chromogen) and ELISA tests respectively, according to the Ig isotype. The results showed a close relationship between ASC numbers and secreted antibody titres. The best in vitro antibody synthesis was observed when the sensitized cells were maintained in contact with virus during the whole culture period. Antibody responses were defined by a kinetic profile characterized by a narrow peak, with a maximum occurring after 4 and 6 days of culture and with the IgA response appearing earlier than the IgG. This methodology, which analyses specific antibody responses at the cellular level, may permit studies on the mechanisms of Ig isotype regulation. Extended to leukocytes from other organs of the immune system, it may also constitute an in vitro model to study antibody responses expressed in different lymphoid tissues of the pig.

Antibody responses to thymic independent antigens in the peripheral and mesenteric lymph nodes of mice

Differentiation of B lymphocytes from various peripheral lymph nodes (PLN) of mice was studied in the in vitro and in vivo conditions. Subcutaneous (SC) immunization in the foot pads with thymic independent (TI)-2 antigens such as polyvinyl pyrrolidone (PVP), R36A, and Trinitrophenyl (TNP)-Dextran failed to elicit plaque forming cell (PFC) responses from the draining popliteal and inguinal lymph nodes, whereas the splenic B cells of these animals exhibited good PFC response. Injection of unconjugated Brucella abortus (BA) along with TNP-Dextran was able to induce anti-TNP PFC formation from the draining lymph node B cells. However, PVP + BA or R36A + BA failed to stimulate such antigen specific B cell responses from the lymph nodes. Since TI antigens are metabolized slowly because of their long repeating subunits, we measured antibody responses up to 8 weeks after SC immunization with TNP-Ficoll and failed to observe any anti-TNP IgM PFC in the lymph nodes. TNP-Ficoll, in contrast to TI-1 antigen TNP-BA, did not induce IgG PFC response in the draining lymph node cells. In in vitro cultures, TNP-Ficoll induced the B cell differentiation from mesenteric lymph node (MLN) cells but not from the PLN cells. This activation of MLN B cells with TNP-Ficoll was limited to normal DBA/2J mice and was absent in the MLN cells of X-linked immune defective CBA/N mice. Finally, there was good antibody response from the inguinal and lumbar lymph node cells after an intraperitoneal immunization with TNP-BA but not with TNP-Ficoll.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of TdT-positive cells in the mesenteric lymph nodes of immunodeficient rats: study of their antigenic phenotype

Terminal deoxynucleotidyl transferase (TdT) containing cells were found in the mesenteric lymph nodes of protein deprived and casein re-fed rats. Double immunofluorescence was used to characterize these TdT+ cells according to their surface antigenic phenotype. TdT+ cells expressing T-cell antigen markers recognized by monoclonal antibodies: W3/13 and OX-19 indicated thymic origin. It was found that these cells represented half the existing TdT+ population in the mesenteric lymph nodes. The rest of them presented the Ia antigen which is coded for by the class II major histocompatibility complex and is recognized by the OX-6 mAb. TdT+ cells presenting the OX-6+ phenotype were ascribed to a bone marrow derived subset. These results indicate that, in some instances, i.e., immunodeficiency due to protein deprivation, TdT+ cells may appear in the mesenteric lymph nodes. Their origin may be attributed either to trafficking of immature cells from the thymus or to cells that leave the bone marrow as a consequence of the damage provoked by protein deprivation.

Influences of the microenvironment on B-cell responses of wasted mice: comparison of Peyer's patches and mesenteric lymph nodes

Wasted mice bear an autosomal recessive mutation (wst/wst) that gives rise to neurologic abnormalities and immunologic deficiency evident as early as 21 days of age. Features of the immune deficiency include absence of plasma cells at mucosal sites, reduction in weight of thymus and spleen relative to body weight, and low serum levels of some immunoglobulin (Ig) isotypes. In these experiments, we have examined parameters of B-cell function in Peyer's patches (PP) and mesenteric lymph nodes (MLN) of wst/wst and age-matched control mice. Our results established the following abnormalities in PP but not MLN of wst/wst mice relative to controls: (1) reduced mitogenic responses to lipopolysaccharide, (2) decreased percentages of Ig+ cells, (3) increased percentages of B-cells bearing large amounts of surface Ig ("very bright" Ig+ cells), and (4) reduced levels of all Ig-specific messenger ribonucleic acids (mRNAs) except alpha-mRNA. The only immunologic abnormality consistently expressed in lymphocytes from both MLN and PP of wst/wst mice is reduced levels of IgA+ B cells and alpha-mRNA. Morphologic studies revealed no consistent abnormalities in lymph nodes, spleens, livers, or PP of wst/wst mice when compared to littermate controls. These results support the idea that some of the immunologic abnormalities reported in wst/wst mice are due to microenvironmental influences. Of the parameters examined in this report, only reduced IgA (mRNA levels and percentage of positive cells) is consistently observed in PP, MLN, and spleen.

Histamine release from human adenoidal and mesenteric mast cells induced by bacterial antigens

The histamine-releasing capability of Staphylococcus aureus antigens was examined in human adenoidal and mesenteric mast cells obtained by enzymic dispersion of tissues from non-allergic patients. Both populations of mast cells released histamine after challenge with bacterial protein in concentrations between 5-500 micrograms/ml. The release was dependent on the dose, temperature and metabolic energy. The maximum release was observed at 15 min after challenge. The present results suggest that Staphylococcus aureus antigens release histamine from human adenoidal and mesenteric mast cells via a non-cytotoxic, active secretory process.

The ontogenetic development of macrophage subpopulations and Ia-positive non-lymphoid cells in gut-associated lymphoid tissue of the rat

The ontogenetic development of macrophage subpopulations and Ia-positive non-lymphoid cells was studied in gut-associated tissue in fetal and neonatal Wistar rats. A two-step immunoperoxidase method was carried out on cryostat sections, a panel of monoclonal antibodies being applied and aimed specifically at rat macrophages (ED1, ED2 and ED3) and at Ia antigen (Ox4). The first ED1-positive macrophages appeared in the liver on Day 15 (gestational age), and they did not express Ia. In developing mesenteric lymph nodes and in the gut wall, macrophages were found for the first time on Day 17 and 18, respectively, of gestation. These early macrophages were also ED1-positive. Until birth, ED2 recognized few cells in the gut-associated tissue; on the day of birth this subpopulation showed a sudden and considerable increase. The distribution pattern of ED3-positive macrophages appeared to be the same in fetal and in adult rats; it was confined to lymph nodes and Peyer's patches. Ia-positive non-lymphoid cells appeared in the abdomen early in ontogeny. The first Ia-positive cells displayed dendritic features and were found on Day 15 of fetal life in the mesenchymal tissue between intestinal loops. A few days later, many Ia-positive cells with a dendritic appearance were demonstrable in the gut wall and in developing mesenteric lymph nodes. Their number increased rapidly during the following days. Based on these results, the existence of two differentiation lines for dendritic cells and classical macrophages is discussed. The function of early Ia-positive cells in the abdomen is suggested as not being an antigen-presenting one.

Expression of autoantigens in human colorectal carcinomas. Implications for a generic vaccine

The antibody response of patients was used to characterize the autoantigens in human colorectal carcinoma. Twenty-seven primary and 13 metastatic carcinomas with paired normal tissues were extracted and transferred onto nitrocellulose membranes by the Western transfer technique. After the transfers were incubated with the serum of the patient from whom the tumor was derived, autoantigens were identified by indirect immunoperoxidase staining. All tumors contained at least one autoantigen. Six tumor-associated autoantigens, ranging in molecular weight from 26 to 58 kilodaltons (kD), were identified by antibodies in 25% or more of the sera. Eleven metastases expressed a 41-kD autoantigen that was present in only a third of the extracts of normal liver or lung. Thus, the number of dominant polypeptide autoantigens in colorectal carcinoma is restricted to six molecules. These autoantigens may be organ-associated antigens that are expressed by neoplastic cells. The 41-kD autoantigen may be a potential marker for metastases. A generic vaccine appears to be feasible for colorectal carcinoma since the number of dominant antigens is limited.

Natural killer cell activity and autologous mixed lymphocyte response of splenic, mesenteric lymph node, and colonic lymphocytes during DMH-induced colon carcinogenesis in the rat

Two in vitro models of immune surveillance were used to examine the immune status of the gut-associated lymphoid tissue, mesenteric lymph nodes, and spleen during the early stages of 1,2-dimethylhydrazine (DMN)-induced colon tumorigenesis. DMH- and vehicle-treated Fischer rats were sacrificed at one of three time points: one week, two months, or five months after cessation of treatment. Colonic, lymph node, and splenic natural killer cell cytolytic activity toward YAC-1 tumor targets and T-cell response to autologous Ia-induced blastogenesis were measured at each time point. We found little change in natural killer cell activity or T-cell proliferation induced by autologous Ia gene products at these time periods.

Immunopathology of experimental Schistosoma mansoni: immunohistochemical localization of parasite antigens in the host tissue

Schistosoma mansoni antigens play a crucial role in the induction of immunopathological processes and in modulating the host immune system. A polyclonal rabbit antiserum to an antigenic fraction of adult schistosoma worms was used to localize worm and egg antigens in tissue sections of infected mice. Most granuloma formations identified in paraffin sections of portal tracts and intestinal mucosa were vigorous with florid cellular composition, consisting of macrophages and epithelioid cells, surrounding a central nidus of S. mansoni egg. Schistosome pigments were demonstrated at the periphery of the granuloma, within sinusoidal Kupffer's cells and within macrophages of intestinal mucosa. Large amounts of schistosome antigen were found sequestered in the mesenteric lymph nodes and in the spleen. A strong reaction for locally synthesized IgG was found. These findings suggest that the schistosome antigen-antibody complex found in the host lymphoreticular system plays a major role in the immunopathological process.

Natural cytotoxic T cells (NCTC) that differ from natural killer (NK) and natural cytotoxic (NC) cells are present in Peyer's patches of mice

We have examined noninduced cytotoxicity of mouse gut associated and peripheral lymphoid tissues for a wide variety of syngeneic as well as allogeneic cell lines and lymphoblasts. Lymphoid cells from Peyer's patches were found to lyse these targets in a 3-hr chromium release assay whereas lymphoid cells from intestinal mucosa, mesenteric or peripheral lymph nodes, spleen, and thymus did not. The variety of targets toward which Peyer's patch cells were cytotoxic established the latter as nonspecific and H-2 unrestricted. The cell responsible for the lytic event was identified as possessing Thy 1.2 and Ia surface antigens. This naturally cytotoxic T cell (NCTC) was found to be adherent to nylon-wool but not to plastic plates. Although both natural killer cell (NK) and non-NK targets served as targets for the NCTC, the latter were further differentiable from NK cells by lack of asialo GM1 surface marker, which is present on NK cells. In addition, NCTC remained fully functional in mice given either of the drugs cyclophosphamide or cortisone. Each of these drugs, in the doses used, markedly reduced poly(I:C)-induced NK activity. Thus, NCTC differs from NK on the basis of the spectrum of targets against which it is functional, phenotypic surface markers, insusceptibility to stimulation with poly(I:C), and insensitivity to diminution by the immunosuppressive drugs cyclophosphamide and hydrocortisone. Since NCTC is a Thy 1.2 antigen-bearing cell and is detectable in a 3-hr cytotoxic assay, it also differs from the natural cytotoxic (NC) cell. NC lacks the Thy 1.2 marker and becomes detectable only in an 18-hr cytotoxic assay. Thus, NCTC is neither an NK nor an NC cell. We have discussed the possibility that the three naturally occurring cells may be related by being dedifferentiated descendants of an antigen-specific cytotoxic T lymphocyte (CTL). Alternatively, since NCTC is confined to an anatomical site prone to ample antigenic exposure and is still identifiable as a T cell, it may be in linear transition from the CTL to the NK or NC stages.

T lymphocytes in the intestinal epithelium and lamina propria of mice

Mesenteric lymphoblasts have a predilection to localize selectively in the murine small intestine within 24 hr after adoptive transfer. In this report, we quantify the localization and intraintestinal distribution of radiolabelled mesenteric lymph node (MLN) T and B blasts in relation to the in situ distribution of intestinal T and B cells which were detected immunohistochemically. Our results show that, within 24 hr after transfer, MLN T blasts localized predominantly in the intestinal epithelium and villus lamina propria, whereas B blasts were found mostly in the basal lamina propria of the gut. In the epithelium and villus lamina propria, 100% and 68%, respectively, of labelled were of thymic origin; this cell type comprised 54% of labelled cells in the basal lamina propria. This pattern of localization was the reverse of the distribution of T lymphocytes and B-cell derived plasmacytes residing in the intestinal wall. These results suggest that MLN T lymphocytes may be a component of common mucosal immunological system and may be integrated with peripheral immunity according to the immunological needs of the host.

Lack of mast cell reactivity during leukemic infiltration of the rat mesentery under syngeneic and allogeneic conditions. A study by transmission electron microscopy (TEM)

The ultrastructural morphology of mast cells localized in rat mesenteries was studied after intraperitoneal implantation of L5222 rat leukemia cells in syngeneic and allogenic hosts. It became evident that the mast cells in the syngeneic (BDIX rat) as well as the allogeneic system (BN rat) showed nor morphological alterations. Degranulation was never observed. This is in contrast to the behavior of macrophages which displayed a strong phagocytotic activity in allogeneic hosts. Thus, it seems that mast cells, under the present experimental conditions, remained inactive during a phase of intense tumor rejection.

[Reactivity of the lymph nodes of the root of the mesentery in the small intestine of rats with alloxan diabetes]

Insulin role in regulating the immunocompetent tissue structure was studied on experimental rats with alloxan diabetes. Tendency to a decrease in the mesenteric lymph node cortical area, accompanied by a fall in the small lymphocyte number, was observed. The lymphatic follicle area markedly diminished. The small lymphocyte and reticular cell content among cellular elements of the clear centers significantly augmented, whereas mitosis number and the percentage of mean and large lymphocytes decreased. Billroth's strand area diminished by one-third comparatively to that of the control. Simultaneously their number of plasma cells and small lymphocytes lowered. Therefore, alloxan diabetes is accompanied by a fall in the parameters of the thymus-dependent structural components of the mesenterial lymph nodes. Insulin deficit induces a decrease in the number of lymphocytes, capable of proliferation and diminishes their mitotic activity.

Separation of mouse lymphoblasts by discontinuous density centrifugation on Percoll gradients

Mouse lymphoblasts generated in vivo by a topical application of the contact sensitizer oxazolone or by the contents of the gut lumen were separated by discontinuous density centrifugation on Percoll gradients. A 3-step gradient was used to divide the cells into two subpopulations. For cells from oxazolone stimulated lymph nodes, the low density band contained 20-30% of the initial cell number applied to the gradient; 25-40% of this population were in S phase and nearly all the large and pyroninophilic cells were confined to this layer. The high density step cells (70-80% of initial cell number) were predominantly small lymphocytes with less than 0.5% in S phase. Similar results were obtained using cells from picryl chloride stimulated lymph nodes or from mesenteric lymph nodes.

Differences in the migration of B and T lymphocytes: organ-selective localization in vivo and the role of lymphocyte-endothelial cell recognition

The migration of B and T lymphocytes in the mouse has been studied by using 1) short-term in vivo homing studies, and 2) an in vitro assay of lymphocyte binding to specialized lymphoid organ venules (post-capillary, high endothelial venules (HEV)) in frozen sections of lymph nodes and Peyer's patches. The homing characteristics of B and T cell populations are largely independent of their organ of origin. B cells from any source distribute preferentially to Peyer's patches, whereas T cells home preferentially to peripheral lymph nodes. This organ specificity of migration appears to be determined at the site of lymphocyte exit from the blood by selective recognition of organ-specific determinants on the endothelial cells of HEV. In addition, the in vivo tendency of B cells to migrate preferentially to the spleen, and of T cells to localize better in lymph nodes is confirmed. The results indicate that, in a hypothetical situation in which an equal number of B and T lymphocytes localized in peripheral lymph nodes (or bound in vitro to peripheral node HEV), there would be about 2.5 B cells for every T cell in the mesenteric node, four to six B cells per T cell in Peyer's patches, and seven to nine B cells per T cell in the spleen. Comparison of these homing preferences with the distribution of B and T lymphocyte populations in situ suggests that selective lymphocyte migration may help determine the proportions of functionally distinct lymphocyte classes in particular lymphoid organs or sites of chronic inflammation, and thus may serve to influence the character of local immune responses.

Impaired intestinal localization of mesenteric lymphoblasts associated with vitamin A deficiency and protein-calorie malnutrition

We examined whether protein-calorie (PC) and vitamin A (VA) deficiencies altered the intestinal localization of mesenteric lymph node (MLN) lymphoblasts using an adoptive lymphocyte transfer method. MLN cells from donor rats were labelled in vitro with [125I]-deoxyuridine and injected i.v. into various recipients. Twenty-two to twenty-four hours after transfer of labelled cells prepared from PC-deficient donors, the percentage of radioactivity in the small intestine of normal recipients was two-thirds of that detected after transfer of cell obtained from normal donors. When donor cells were obtained from rats suffering both PC and VA malnourishment, this decrease was even greater, being only one-third of the normal donor cell control. Other experiments indicated that the defect in localization behaviour was associated with the donor blasts and not the recipient intestine. These findings suggest that defective localization in mucosal lymphoblasts may be a factor contributing to morbidity in malnourished populations.

Sequential mesenteric lymph node histological response following Trichinella spiralis infection

The histology of mouse secondary lymphoid tissue was examined following infection of Trichinella spiralis. ICR/CD-1 mice were orally infected with 200 T. spiralis and sacrificed at either 0, 3, 7, 14, 28 or 56 days after nematode administration. The animals were bled and sacrificed, and mesenteric lymph nodes were removed from each animal. They were fixed in 10% neutral buffered formalin, embedded in paraffin, and cut in 4-micron sections. Examination of serial sections demonstrated the sequential development of histological alteration in these regional lymph nodes. Hyperplasia was detected as early as 3 days after infection. Progressive changes occurring between 7 and 28 days after larval inoculation included hyperplasia with concurrent congestion of medullary sinuses, with increased numbers of neutrophils, histiocytes, lymphocytes, and eosinophils. Microscopic appearance of nodes removed from 56-day infected mice was similar to that noted for control tissues.

Simultaneous induction of antigen-specific IgA helper T cells and IgG suppressor T cells in the murine Peyer's patch after protein feeding

The effects of feeding the dietary protein antigen, ovalbumin (OVA), on OVA-specific IgG and IgA immune responses involving Peyer's patches (PP) and mesenteric lymph nodes (MLN) were examined. Mice were administered soluble OVA by gastric intubation. One to 3 days later, PP, MLN, or spleen cells from these donor mice were adoptively transferred into normal syngeneic recipients. After two subsequent immunizations, spleens from the recipient mice were assayed for IgA and IgG anti-OVA plaque-forming cell (PFC) responses. None of the tissues from normal (unfed) mice had the inherent ability to alter recipients' IgG or IgA PFC responses. Within 1 day of OVA feeding, however, cells were generated in the PP that could augment recipients' IgA anti-OVA PFC responses and suppress IgG PFC responses. Three days after OVA feeding, these cells were present in MLN as well, and whereas the IgG suppressor cell also appeared to migrate to spleen, the IgA helper cell did not. The cells mediating antigen-specific IgG suppression and IgA help were both T cells but could be distinguished by surface phenotype. We therefore conclude that protein feeding induces differential, isotype-specific immunoregulation in gut-associated lymphoid tissues, part of which is mediated by an antigen-specific IgA helper T cell.

Lack of age-associated immune dysfunction in mucosal-associated lymph nodes

The magnitude of the immune response in old and young mice to trinitrophenylated bovine gamma-globulin was measured in various lymphatic sites at a cellular level using the plaque-forming cell assay. As we have previously shown, the number of splenic IgM, IgG, and IgA anti-TNP PFC progressively declined in aging C57BL/6J male mice. In addition, mice receiving antigen in the 4 footpads and the base of the tail exhibited similar decline in the number of PFC in the draining peripheral lymph nodes with increasing age. In contrast, mesenteric and mediastinal lymph node IgM, IgG, and IgA anti-TNP PFC response to TNP-BGG in complete Freund's adjuvant, i.p. or via gastric intubation, in old mice remained unimpaired compared with the number in younger mice. The data support the view that the mucosal-associated lymphoid system differs from the systemic system with regard to immune competence with age. Furthermore, the findings imply a site preference for a decline in immune function with aging.

Route of lymphocyte migration in pigs. II. Migration to the intestinal lamina propria of antigen-specific cells generated in response to intestinal immunization in the pig

Intestinal lymph-duct cannulae were established in normal and mesenteric lymphadenectomized (MLNx) pigs for the 6-day duration of a local intestinal immune response to a protein antigen (ovalbumin). The daily output of anti-ovalbumin-containing cells (AOCC) in intestinal lymph and the numbers of AOCC in the intestinal lamina propria at the end of the experiment were recorded. Very few AOCC were recovered in the intestinal lymph of normal pigs whereas in MLNx pigs large numbers were recovered reaching a peak output on day 4. However, there were significantly more AOCC detected in the jejunal lamina propria of normal pigs than MLNx pigs despite continuous drainage of intestinal lymph throughout the response. The absence of AOCC from efferent intestinal lymph of normal pigs, the failure of chronic intestinal-lymph drainage to abrogate the AOCC response in the intestine of these pigs and the reversal of these findings in MLNx pigs indicate that, in contrast to other species, lymphoblasts are diverted from porcine intestinal lymph, and probably enter the blood circulation at the level of the mesenteric lymph node (MLN).

[Morphological studies in delayed hypersensitivity to streptococcal antigens using film preparations of the mesentery]

Film preparations of the mesentery were used for morphological study of cell reactions, connected with the delayed type hypersensitivity (DTH). Twenty-four hours after intraperitoneal injection of small doses of the streptococcal thermostable fraction (TST fraction) the guinea-pigs sensitized with streptococcal culture developed a more intensive, as compared with control animals, diffuse infiltration of the peritoneum with mixed type cells (lymphocytes, monocytes and polynuclear leukocytes) abundant in mononuclear elements. With TST fraction dose build up the infiltration demonstrated an abrupt increase in polynuclear leukocytes completely masking the monocytic reaction in some cases. Large aggregations of lymphocytes were seen in the prelymph sinuses accompanying blood capillaries and nervous stemlets. Detection in the peritoneum of cell reactions characteristic of DTH following the injection of certain doses of specific antigens and comparative simplicity of obtaining film preparations allow recommending the technique described for disclosing and experimental study of DTH to microbial antigens.

Evidence for a common mucosal immunologic system. II. Influence of the estrous cycle on B immunoblast migration into genital and intestinal tissues

The influence of the estrous cycle on the localization of plasma cell precursors in the genital mucosa was studied in CBA/J female mice by using an adoptive transfer system. Within 24 hr after transfer, [3H]-thymidine-labeled donor mesenteric lymph node (MLN) cells were observed in maximum number in proestral and estral cervices and vaginae (14.4 and 9.7 labeled cells/100 mm2 of tissue, respectively), and approximately 60% of these cells contained IgA and 25% IgG. During metaestrus and diestrus, however, few labeled MLN cells (4.0/100 mm2 of tissue) localized in the genital tract and this reduction affected the IgA-containing plasmacyte population in particular. In contrast, no change was noted in the frequency of labeled cells containing IgA in the small intestine over the course of the estrous cycle, although small but significant changes were noted in the frequency of labeled cells producing IgG. These results indicate that the hormonal changes during the estrous cycle may affect the localization of IgA plasma cell precursors in the genital tract and thus may alter the local mucosal immune response in this site.

Surface markers of porcine lymphocytes and distribution in various lymphoid organs

Three rosette test systems were developed for the classification of subpopulations of porcine lymphocytes and correlated with the presence or the absence of membrane immunoglobulins, as well as agg-P-IgG receptors, by means of various RFC depletion experiments. Among the ED-RFC negative cells, PBL with surface immunoglobulins (SIg), at 4 degrees C, can be subdivided into two about equal populations: (1) One half of these cells have surface stable SIg (B cells) and mu determinants; they possess C3b receptors leading to the formation of rosettes with complement-coated zymosan particles (ZC). (2) The other half have surface labile Ig when the cells are washed at 37 degrees C (L-cells); they possess Fc receptors as detected by EA-RFC, i. e. pig-IgG-coated ox RBC. Receptors for Fc-agg, as detected by agg-P-IgG, were primarily shown on B cells. ZC and EA-RFC are in the highest tissue concentration, in bone marrow and spleen, respectively, and more numerous in adults than in newborns. Moreover, the number of EA-RFC was twofold higher than that of ZC-RFC in spleen, mesenteric lymph node and cisterna chyli. This latter organ was the only one without null cell.

Effect on rat IgA synthesis by isotypic suppression with an anti-rat delta heavy chain serum

It is highly probable that IgA precursor cells have IgD receptors during their ontogeny, however isotypic suppression with anti-delta serum did not demonstrate this possibility at least in our experimental conditions. Moreover, isotypic suppression with anti-delta serum seems ineffective in diminishing the serum levels of Ig classes other than IgD under these conditions, as IgM, IgE and IgG serum levels were relatively unaffected, at least during the first month of the rat life.

Development of the IgA system in the mammary gland

1) Lymphoblasts in gut-associated lymphoid tissue, committed to the production of IgA, can home to the mammary glands of syngeneic mice and differentiate there into IgA-containing plasmablasts. The phenomenon is limited to near term and lactating recipients. 2) The ability of lymphocytes originating in gut-associated lymphoid tissue and sensitized to intestinal antigens to migrate to the mammary gland can account for the specificity of milk IgA toward intestinal microorganisms and the consequent passive protection offered to suckling infants. 3) The secretory immune system of the mammary gland is apparently under hormonal control since mammotropic hormones given to virgin females can induce morphological and functional characteristics seen naturally only during pregnancy and lactation. Examples are increased numbers of IgA plasma cells and the ability to trap their circulating precursors taken from mesenteric lymph nodes.