Immunoglobulin-containing Cells Research Articles

Distribution of lymphocytes, immunoglobulin-containing cells, macrophages, and dendritic cells in the accessory sex glands of rams experimentally infected with Actinobacillus seminis

Abstract: The distribution of cells involved in the immune response in accessory sex glands of rams experimentally infected with Actinobacillus seminis was studied. Twelve one-year old rams were experimentally infected by intraurethral (IU) (n=4) and intraepididymal (IE) (n=4) route, and four control (CON) animals were used. The animals were slaughtered 35 days post-inoculation, samples were taken from accessory sex glands, and bacteriology and histopathology tests were performed. The presence of CD4, CD8 and TCRγδ (WC1) lymphocytes, CD45RO cells, macrophages (CD14), dendritic cells (CD1b), IgA-, IgG- and IgM-containing cells (IgCC) was determined. Animals of the IE group developed clinical epididymitis. No lesions were seen in rams of the IU group; two of the intraepididymal inoculated CON developed small lesions in the epididymis. A. seminis isolates were achieved from 6:16 (37.5%) accessory sex glands in the IE group, but not in the IU and CON groups. In the CON group, IgA- and IgM- containing cells predominated in the bulbourethral glands and the disseminated prostate, and they were scarce or null in the vesicles and ampullae. A significant increase of IgA-, IgG- and IgM- containing cells was confirmed in the seminal vesicles, the ampullae and the bulbourethral glands in the IE group. In the IE and IU groups, an increase in CD4, CD8, WC1, CD45RO and CD14 was evidenced in the vesicles and ampullae. CD1b dendritic cells were present in the ampullae and vesicles with inflammatory processes. A. seminis triggered a local immune response in the IE and IU groups. These results indicate a different pattern of infiltrating immune cells in the accessory sex glands of infected A. seminis rams.

Distribution of immune response cells in the pelvic urethra and the prepuce of rams

The pathogens of the reproductive system in the male can penetrate and establish by ascending route, from to the prepuce to the urethra, accessory glands, epididymis and testicles. The aim of this paper is determine the distribution and number of cells involved in the immune response in prepuce and pelvic urethra of rams, without apparent clinical alterations in testicle, epididymis and prepuce. The distribution of some of the cells involved in the immune response at the level of the prepuce and the pelvic urethra was quantified in four one-year-old rams seronegative for B. ovis and A. seminis and without apparent lesions in the testicles, the epididymis, and the prepuce. At the moment of slaughter, samples were taken from the preputial fornix and the pelvic urethra and placed in 10% formalin and under freezing conditions. CD4, CD8, WC1, CD45RO, CD14 and CD1b cells were demonstrated by immunohistochemistry, and immunoglobulin-containing cells (ICC) of the IgA, IgG and IgM classes were demonstrated by immunofluorescence. The labeled cells present in the mucosa of both organs were counted with an image analyzer. The total number of cells was compared between both tissues and differentially between the epithelium and the connective tissue of the mucosa. Significant differences were found in the total number of CD4, CD45RO, and WC1 lymphocytes, in CD14 macrophages, and CD1b dendritic cells, with mean values being greater in the fornix than in the urethra (p<0.05) in all cases. Only dendritic cells were found in the prepuce. No differences were found in the number of CD8 lymphocytes between both organs. The ratio between each cell type in the connective and the intraepithelial tissues and between organs was 10/1 for CD4 in the fornix (p<0.05), against 7/1 in the urethra (p<0.05), while CD8 had a 1/1 distribution in both mucosae. The WC1 ratio was 5/1 in both mucosae (p<0.05). CD45RO labeling was 19/1 in the prepuce (p<0.05) and 1/1 in the urethra. IgA-containing cells did not show differences in the total number of cells in both tissues. In the urethra, no IgG-containing cells were observed and IgM-containing cells were scarce; in contrast, both cell types were present in the prepuce, in amounts greater than in the urethra (p<0.05). IgA-, IgG-, and IgM-containing cells were located in both organs in the mucosal connective tissue. The presence of antigen-presenting cells, macrophages, and dendritic cells, as well as of lymphocytes CD4, CD8 TCR γδ (WC1), IgA-, IgG and IgM positive cells, and CD45RO cells suggests that both mucosae may behave as inductive and effector sites for the mucosal immune response.

Distribution of mast cell subtypes and immune cell populations in canine intestines: Evidence for age-related decline in T cells and macrophages and increase of IgA-positive plasma cells

The distribution and numbers of leucocytes and mast cells (MC) in the canine gastrointestinal tract of three different age groups was investigated immunhistochemically. In all age groups, CD3+ T cells were more prominent in the villus region than in the crypt areas without differences between intestinal segments, whereas macrophages were more randomly distributed. Kresylecht-violet and tryptase-positive MC were prominent in pericrypt regions with statistic significances. Chymase-bearing mast cells, IgA-, IgG- and IgM-containing cells did not show significant differences in their distribution but, except for IgG-positive cells, subjective trends with increasing numbers towards the crypts exist. The reasons for the distribution of T cells, macrophages, immunoglobulin-containing cells and mast cells are not clear. Lamina propria CD3+ T cells and macrophages significantly decreased whilst a significant increase of IgA-containing plasma cells with increasing age was found. For mast cell subtypes, IgG- and IgM-containing cells no significant changes in numbers with increasing age exist.

Accumulation of immunoglobulin-containing cells in the gut mucosa and presence of faecal immunoglobulin in severe combined immunodeficient (scid) mice with T cell-induced inflammatory bowel disease (IBD).

Scid mice transplanted either with a gut wall graft or with low numbers of purified CD4+ T cells from immunocompetent syngeneic donor mice show clinical signs of IBD 3-4 months post-transplantation. The disease is mediated by mucosa-infiltrating CD4+ TCR alphabeta+ T cells. The pathology of 52 individual colon segments obtained from 20 gut wall- or CD4+ T cell-transplanted diseased scid mice was evaluated by histology and the numbers of infiltrating immunoglobulin-containing cells were determined. In particular, cells positive for IgM, IgA and non-inflammatory immunoglobulin isotypes such as IgG1 and IgG2b were found to accumulate in colon segments displaying the most severe histopathology, including inflammatory cellular infiltration, epithelial hyperplasia and ulcerative lesions. Compared with colon segments of normal C.B-17 mice, the lesional scid colon shows increased levels of cells positive for the IgG classes. Faecal extracts of the CD4+ T cell-transplanted scid mice revealed the presence of all six murine immunoglobulin isotypes. Disease progression was accompanied by an increased level of excreted IgM and IgG3 and decreased levels of IgA. It is concluded that locally secreted immunoglobulins may play an immunomodulating role in the pathological changes observed in the present model of T cell-induced inflammatory bowel disease.

Distribution of T-cell subsets and immunoglobulin-containing cells in nasal-associated lymphoid tissue (NALT) of chickens.

The present study demonstrated the localization of the T-cell subsets (CD4+ and CD8+) and immunoglobulin (Ig)-containing cells (IgA, IgM, and IgG) in the nasal mucosa and its accessory structures. These lymphoid structures may be compared with nasal-associated lymphoid tissue (NALT) of rats and mice. In the chicken NALT, T-cell subsets were more widely distributed than Ig-containing cells, especially in large lymphoid accumulations restricted to the respiratory mucosa in the nasal cavity and the nasolacrimal duct. These lymphoid accumulations in the mucosa of the nasal cavity and nasolacrimal duct consisted of widely distributed CD8+ cells and deeply aggregated CD4+ cells adjacent to large germinal centers. In these lymphoid accumulations, IgG-containing cells were more frequently observed than IgM- and IgA-containing cells. T-cell subsets, predominantly CD8+ cells were more widely distributed in the duct epithelium of the lateral nasal glands than Ig-containing cells. Moreover, numerous CD8+ cells and a few Ig-containing cells were found in the chicken salivary glands, especially around the orifice of their ducts into the oral cavity. Therefore, it seems likely that the chicken NALT plays an important part in the upper respiratory tract, with a close relationship to the paraocular immune system.

Eosinophilia is attenuated in experimental colitis induced in IL-5 deficient mice.

Tissue eosinophilia is a feature of idiopathic inflammatory bowel disease and other forms of colonic inflammation but it is not clear whether the role of eosinophils in the disease process is to contribute to tissue damage. Interleukin 5 (IL-5) stimulates production and activation of eosinophils in vitro and enhances immunoglobulin A (IgA) production. As very little is known about the function of IL-5 in the colon, the aim of this study was to assess its role in colonic inflammation. IL-5 deficient mice were studied using the dextran sulphate sodium (DSS)-induced colitis model and the results compared to a congenic IL-5+/+ strain. The absence of IL-5 resulted in reduction of tissue eosinophilia (P < 0.0001) but was not reflected in differences in the severity of the disease (P > 0.5) or in the extent of tissue damage in this model of colitis. Numbers of immunoglobulin-containing cells in IL-5 deficient mice were similar to those in the IL-5+ mice. We conclude that the main role of IL-5 in DSS-induced colonic inflammation is to attract a population of eosinophils which do not appear to contribute significantly to the initiation or development of tissue damage in this model of colitis.

Colonic lymphocyte and plasma cell populations in dogs with lymphocytic-plasmacytic colitis

Abstract Objectives To quantitate immunoglobulin-containing cells (IgA, IgG, and IgM) and CD3+ T cells in colonic biopsy specimens obtained from dogs with lymphocytic-plasmacytic colitis (LPC), and to compare lymphocyte and plasma cell populations in dogs with LPC with those in healthy dogs. Animals 10 healthy dogs and 11 dogs with LPC. Procedure Colonic mucosal specimens obtained from healthy dogs and dogs with LPC were stained specifically for IgA-, IgG-, and IgM-containing cells and CD3+ T cells by use of immunoperoxidase techniques. Morphometric analyses were done to quantitate lymphocytes and plasma cells in standardized areas of colonic mucosa. Data analyses allowed determination of mean cell numbers in each dog group, and comparison of mean numbers of lymphocytes and plasma cells between dog groups. Results CD3+ T cells predominated in healthy dogs, whereas CD3+ T cells and IgA-containing cells were most numerous in dogs with LPC. In both dog groups, the IgG- and IgM-containing cells were considerably less numerous than the other 2 cell types. Comparison of cell populations between dog groups indicated that IgA- and IgG-containing cells and CD3+ T cells were significantly more numerous in the colonic mucosa of dogs with LPC. Conclusions Dogs with LPC have significantly increased numbers of IgA- and IgG-containing cells and CD3+ T cells. These lymphocyte and plasma cell distributions indicate similarities to and differences from such distributions in human beings with inflammatory bowel disease. Results provide a basis for future correlation between histologic stage of disease activity and immunologic findings in dogs with LPC. (Am J Vet Res 1999;60:515-520)

Effects of ageing and oestrogen on the localization of immunoglobulin-containing cells in the chicken ovary.

Immunoglobulins in the chicken ovary are important for transfer of immunity to chicks through the egg and for protection of the ovary from infection. The aim of this study was to examine the effects of ageing and oestrogen on the population of Ig-containing cells in the chicken ovary. The ovarian tissue of immature, young laying and old laying hens and that of immature birds treated with diethylstilboestrol (DES), progesterone or sesame oil (vehicle) was processed for paraffin wax sections. The sections were stained for IgG, IgM and IgA by an indirect immunostaining method and the population of cells positive for each Ig was analysed under a light microscope. The number of cells positive for IgG, IgM and IgA was significantly greater in the ovarian stromal tissue of young laying hens than in immature or old laying hens (P < 0.01). The number of IgG- and IgM-positive cells in the thecal layer of primary follicles of young laying hens was significantly greater than that in immature and old laying hens (P < 0.01) and there were significantly more (P < 0.05) IgA-positive cells in young laying hens than in immature birds. The number of IgG-, IgM- and IgA-positive cells was significantly (P < 0.01) greater in both the stromal tissue and the thecal layer of DES-treated birds than in the vehicle-treated birds. Progesterone had no significant effect (P < 0.05) on the population of Ig-positive cells. These results indicate that the number of Ig-positive cells increases as chickens mature and decreases with ageing, and that oestrogen may be involved in this process.

THE MUCOSAL AND SYSTEMIC IMMUNE RESPONSES IN CHICKENS ORALLY IMMUNISED WITH CAMPYLOBACTER JEJUNI ANTIGEN ENTRAPPED IN POLY-LACTIDE-CO-GLYCOLIDE MICROPARTICLES

An oral immunisation in chickens with antigen entrapping in biodegradable microparticles was evaluated in order to achieve optimal antibody responses following oral vaccination. This study was adapted to Campylobacter jejuni antigen in chickens to observe its stimulation both mucosal and systemic immune responses. A group of 5 embryonated chicken eggs was immunised with heat-killed C. jejuni entrapped in poly-lactide-co-glycolide (PLG) microparticles at day 17 of incubation deposited into the amniotic fluid. Seven days after hatching the chickens were oral boostered, these was design to as Group A. In the Group B, each embryonated egg was immunised with soluble C. jejuni as in the same as Group A. Immune responses of post vaccination were observed at day-14, the humoral immunity was evaluated with an ELISA and whereas mucosal antibody response was detected by fluorescent histology. The serum IgG and IgA antibody responses, and also the bile and intestinal scrapping IgA antibody responses to campylobacter in Group A were significantly higher than those of the soluble antigen of Group B (P<0.05). Total number of immunoglobulin-containing cells for IgG, IgM, and IgA isotypes in the ileum in Group A chickens were also significantly higher than those of Group B (P<0.05) but was not in the duodenum and spleen. Key words : Campylobacter jejuni , poly-lactide-co-glycolide microparticles, oral immunisation, chickens

Reversal of altered intestinal mucosal immunity in rats fed elemental diet by supplementation of oleic acid.

We have previously demonstrated that elemental diet (ED) induces decreased lymphocyte transport in intestinal lymph and significant changes in T cell subsets and the number of IgA-containing cells in gut-associated lymphoid tissues of rats. In order to examine whether the low fat content contributes to the induction of immunological changes in gut-associated lymphoid tissues, the effects of additional fatty acid in the ED were investigated. Rats were divided into four groups: elemental diet alone, elemental diet supplemented with 5% oleic acid (OA), elemental diet with 10% OA and conventional diet as a control. These diets were given at the same daily calorie intake for 4 weeks. The flow rate of intestinal lymph showed no significant difference between the four groups. However, lymphocyte flux as well as the percentage of CD3+ and CD4+ cells were significantly greater in the control and the 10% OA groups than in the ED and 5% OA groups. Intestinal lymph showed decreased concentrations of IgG and IgA in the ED group, whereas the addition of 10% OA significantly attenuated the decrease in these levels. In mesenteric lymph nodes, the CD4+/CD8+ ratio was significantly decreased in the ED group, but 10% OA reversed this change. Immunohistochemical analysis of the ileal mucosa showed that in the ED group the population of CD4+ cells was decreased, while the number of CD8+ cells was increased. Supplementation of OA to ED produced similar stepwise attenuation of the changes in lymphocyte subpopulations in the lamina propria, while the 10% OA group reached levels that were not statistically different from controls. In the elemental diet group, there was a significant decrease in immunoglobulin-containing cells of the IgA class in the lamina propria of the intestine. Similarly, the addition of OA induced dose-dependent recovery in the number of IgA-containing cells. These results suggest that a low dietary concentration of fat may be closely related to changes in lymphocyte transport in intestinal lymph and mucosal immunity of intestinal mucosa induced by the feeding of a long-term ED.

Population changes in immunoglobulin-containing mononuclear cells in dextran sulfate sodium-induced coltitis.

To investigate the relation of immunoglobulin-containing cells in the colonic mucosa to mucosal inflammation, we immunohistochemically examined the localization of immunoglobulin-containing mononuclear cells in the lamina propria in dextran sulfate sodium induced colitis in mice. Mice were treated repeatedly with 3% dextran sulfate sodium (MW 54,000) solution or distilled water for a total of 170 days (chronic model), or for 85 days (subacute model) or for 10 days (acute model). IgG, IgA, and IgM-containing mononuclear cells were studied by enzyme immunostaining. The number of IgA- and IgG-containing cells gradually and significantly increased in the acute, subacute, and chronic models, in that order (P < 0.01 or 0.05). However, the numbers of IgM-containing cells in the three models were similar to that in the controls. These findings resembled those of human ulcerative colitis. In this dextran sulfate sodium-induced colitis, IgA-containing mononuclear cells may play an essential role in the mucosal immune system is the acute, subacute, and chronic phases. The finding that IgG-containing mononuclear cells increased substantially in the chronic phase suggests that IgG plays an important role in the mucosal inflammatory reaction during the chronic phase.

Flow cytometric quantification of lymphocyte subpopulations and immunoglobulin-containing cells in adenoid tissue in relation to secretory otitis media and age.

This study was designed to identify differences in the immunological reactions in adenoid tissue between children suffering from chronic secretory otitis media (SOM) and control children without ear disease. Cell populations were identified using monoclonal antibodies and flow cytofluorometry to facilitate quantitative comparisons. A modification of the FOG method was developed to quantify lymphocytes with intracellular IgG and IgA. Immunological screening was done in the first part of the study. No significant differences were found between the groups regarding cells positive for CD3, CD4, CD8, CD20 or CD25. A significantly higher number of PCA-1 positive cells (presumably plasma cells) were found in the SOM group. The second part of the study concentrated specifically on cells containing IgG or IgA. No statistically significant differences in number of positive cells were found between the groups. When we related the percentage of positive cells to age, a statistically significant decrease with age for IgA-positive cells was found in the SOM group but not in the control group. This result supports the hypothesis that SOM is associated with an immunological reaction that influences immunoglobulin production in adenoid tissue.

Immunohistochemical evidence that gonads and gonad-associated tissues are sites for enrichment with immunoglobulin-containing cells in adult chickens.

Immunohistochemical staining of tissue sections prepared from gonads and gonad-associated tissues obtained from adult chickens was performed in order to assess the possibility that these tissues may be sites of enrichment with IgM-containing cells in various B lineages. Evidence is presented which suggests that IgM-containing B lineage cells are present in 1) the ovarian stroma and subcapsular areas of the ovary and 2) the interstitium and subcapsular areas of the epididymis of the testes. These represent new sites reported for B lineage cells in adult chickens. Some questions relevant to the physiologic, ontogenetic, and phylogenetic implications of these observations relative to vertebrate hematolymphopoietic processes are included.

Antibody-producing cells in peripheral blood and tonsils after oral treatment of children with bacterial ribosomes

The efficacy of ribosomal preparations as mucosal immunostimulants was examined in the peripheral blood and tonsils of 14 children, before and after 28 days of oral treatment with D-53, a preparation of ribosomes from Klebsiella pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes. Tonsils from 10 untreated children were used as controls. Immunofluorescence and ELISAspot were performed to analyse variations in the numbers of immunoglobulin-containing and immunoglobulin-secreting B-cells. Both isotypic and antigenic specificities of these two types of cells were investigated. Significant differences were observed after treatment in the peripheral blood as well as between tonsils from treated and untreated children. In the peripheral blood a significant increase in immunoglobulin-secreting cells directed against antigenic specificities of D-53 was the major change. In tonsils, higher numbers of specific immunoglobulin-containing and secreting cells, and higher numbers of IgA-secreting cells were induced in treated children. These data support the efficacy of D-53 as an oral immunostimulant.

Antibody-containing cells in the abomasal mucosa of sheep with genetic resistance to Haemonchus contortus

The frequency distribution of parasite-specific antibody-containing cells ( ACC) and total immunoglobulin-containing cells ( ICC) in the abomasal mucosa was examined in genetically resistant and random-bred sheep, following infection with Haemonchus contortus, to determine whether the two genotypes differed in the development of a local immune response. Immunofluorescence staining was used to detect ACC and ICC of IgA, IgG 1, IgG 2 and IgM classes. No ACC were found in the abomasum of any of the sheep before infection. ACC were first detected in the abomasal mucosa of both the resistant and susceptible sheep seven days after infection, reached a peak level on day 21 and then declined. At all observation times, the majority of ACC in both genotypes were of the IgA isotype, followed by IgG 1 and IgM. The IgG 2-ACC response was negligible compared with the IgA and IgG 1 response. The comparison of genotypes showed that the resistant sheep had significantly more IgA- ACC on days 14, 21, 28 and 35, and significantly more IgG 1-ACC than random-bred sheep on days 14, 21 and 28. The numbers of IgG 2- and IgM- ACC did not differ between the genotypes. The abomasal mucosa of the resistant sheep was also found to have significantly more ICC than the mucosa of random-bred sheep; IgA- ICC predominated at all the observation times followed by IgG, and IgM. These results suggest that IgA and IgG 1 antibodies, produced locally in response to infection, may play a role in mediating genetic resistance to haemonchosis in sheep.

Identification of cell types present in bovine haemolymph nodes and lymph nodes by immunostaining

Mediastinal haemolymph nodes (HN) and lymph nodes (LN) of 15 healthy calves and ten healthy steers and 53 steers with respiratory diseases (pneumonias) were studied using monoclonal antibodies (Mabs) specific to bovine B and T lymphocytes: BAQ155A (B), CH128A (BoCD2), CACT138A (BoCD4), CACT80 (BoCD8), BAQ4A (Null cells). Topographical distribution of the HN T and B cell subset appears similar to the distributions in the LN. The germinal centres contained B+, BoCD2+ and BoCD4+ cells, whereas no staining of lymphocytes could be seen in the mantle zone. BoCD2+, BoCD4+ and BoCD8+ lymphocytes were located in the parafollicular lymphatic tissue, whereas B and Null lymphocytes were scattered. The same pattern was observed in the hyperplastic haemolymphadenitis of steers with respiratory diseases with an increased positive staining for BoCD4 and BoCD8. A similar pattern was observed for HN and LN Immunoglobulin Containing Cells (ICC). Furthermore, in the calf HN, IgM positive ICC were the most frequent class (44% in HN vs. 33% in LN). It is likely that they could contribute to produce a particularly efficient primary immune response. This is the first study of the distribution of different lymphocyte phenotypes in mammalian haemolymph nodes.

Detection of Akabane viral antigen and immunoglobulin-containing cells in ovine fetuses by use of immunoperoxidase staining

SUMMARY Akabane virus (akv) strain OBE-1 was inoculated IV into 17 pregnant sheep. Ten fetuses infected at 29 to 45 days of gestation and examined 29 to 30 days later had AKV antigen in the following groups of cells: neuroglial cells in the brain and spinal cord, ganglion cells in the cranial and abdominal ganglia, layer of ganglion cells in the retina, ganglion cells (Auerbach's plexus) in small intestine, hepatocytes, cells in the arterial wall of mesenteric membrane, and trophoblast cells in the placenta. Prior to detection of circulating virus-neutralizing antibody, immunoglobulin-containing cells were found initially at 59 days of gestation in the peripheral portion of white pulp tissue in the spleen. After that, numbers of immunoglobulin-containing cells gradually increased. These results indicated that akv may have strong affinity for neuronal and ganglional cells in infected fetuses and immunoglobulin-containing cells might be considered the earliest immunologic response to AKV replication in the fetus.

In situ characterization of gingival mononuclear cells in rapidly progressive periodontitis.

Rapidly progressive periodontitis (RPP) has been suggested as a distinct clinical entity within the spectrum of early onset periodontitis. Immunological mechanisms have been considered in the pathogenesis of RPP. This study was designed to evaluate the distribution and phenotypic properties of the lymphocyte populations within the affected gingival tissue of patients with RPP. Biopsies were obtained from 16 patients between 22 and 33 years of age. The tissue samples were processed for both histopathological and immunohistochemical examinations. Gingival tissue T lymphocytes (CD3+), helper T cells (CD4+), suppressor-cytotoxic T cells (CD8+), and cells positive for HLA-DR antigen were identified using monoclonal antibodies with an immunoperoxidase technique. Intracytoplasmic immunoglobulin-containing cells were also stained immunohistochemically with polyclonal antibodies. CD3+ cells were mainly located beneath the pocket epithelium. CD4+ and CD8+ cells were evenly distributed within this T-cell infiltrate with a CD4+/CD8+ ratio of 1:12. Numerous HLA-DR+ cells were also observed in the lymphocytic infiltrates. The majority of mononuclear cells located throughout the stroma were IgG+ plasma cells. Our results indicate that RPP patients present an IgG-bearing plasma cell dominated lesion with equal participation of both T-cell subpopulations. These findings suggest that activation and proliferation of B-cells play an important role in the pathogenesis of periodontal diseases.

Development of the B- and T-cell compartments in porcine lymphoid organs from birth to adult life: an immunohistological approach

Using immunohistological techniques, we studied the development over time of B- and T-cell compartments in the lymphoid organs of specific-pathogen-free pigs. Tissue samples were collected at various time-points, starting 2 days before the pigs were born until the pigs were 10 months old. The samples were collected from the spleen, thymus, peripheral lymph node, mesenteric lymph node, duodenum, jejunum, ileum, jejunal Peyer's patch and ileal Peyer's patch. Monoclonal antibodies specific to B- and T-cells were used to identify where the following cells were localized: IgM-B cells (cells positive to surface immunoglobulin), IgM-, IgG- and IgA-containing cells (cells positive to cytoplasmic immunoglobulin), and CD2-, CD4- and CD8-positive cells. The development of the B- and T-cell subpopulations in each organ was analysed. Two days before birth, most organs contained quantities of IgM-B cells. The spleen, lymph nodes, Peyer's patches and, notably, the thymus, contained some immunoglobulin-containing cells (Ig-CC); this finding indicates that pigs have cells that secrete immunoglobulins before birth. Just after birth, the incidence of Ig-CC increased in most organs; first IgM-CC increased, then either IgG- or IgA-CC increased, depending on the organ. T-cell development was observed clearly in spleen and in the lamina propria of the small intestine, in contrast to other organs, in which the T-cell compartments containing various T-cell subpopulations were well developed before birth. Comparison of the incidence of CD4 + and CD8 + cells showed that the CD4:CD8 ratio of these cells in the spleen, lymph nodes, Peyer's patches and small intestine is low, especially in adult pigs, compared with the CD4:CD8 ratio in other species. Weaning had little influence on the incidence of B- and T-cells in lymphoid organs. This study is the first immunohistological survey to describe the development of the major B- and T-cell subpopulations in various lymphoid organs of pigs, and it should be useful for future immunopathological and comparative immunological studies in pigs.

Immunopathology in Aujeszky's disease virus-infected pigs exposed to fluctuating temperatures

Pigs exposed to fluctuating temperatures (high, 30±2°C; low, 4±1°C) were intranasally inoculated with Aujeszky's disease virus (ADV). ADV-infected pigs, exposed to the fluctuating temperatures, showed severe clinical signs and ADV in the nasal secretions persisted longer than in the ADV-infected control pigs kept at the normal temperature (20±2°C). High concentrations of ADV were isolated from nasal secretions on the 1st day after inoculation of the virus. Pathologically, all ADV-infected pigs had non-suppurative encephalitis and trigeminal ganglionitis. The lesions were more widely distributed in pigs exposed to fluctuating temperatures than in infected control pigs. Two infected pigs given the stress had severe malacic foci in the frontal lobe and four of them had prominent interstitial pneumonia. In the pigs exposed to fluctuating temperatures, a significant number of immunoglobulin-containing cells, especially IgM-containing cells, did not respond to ADV infection. A significant ( P<0·01) difference in the number of IgG- and IgM-containing cells was observed between the ADV-infected pigs exposed to the fluctuating temperature and ADV-infected control pigs, respectively. These results demonstrated that the stress of fluctuating temperatures enhanced the susceptibility to ADV infection.