Origins of serum IgE and of the homocytotropic antibody-secreting cells in the thoracic duct lymph of rats infested with Nippostrongylus brasiliensis

Mast cell hyperplasia in Opisthorchis viverrini-associated cholecystitis

Despite significant advances in understanding the role of the immune response in Opisthorchis viverrini-associated carcinogenesis, little is known about how infection induces gall bladder disease. This study investigated whether mast cells are activated in cholecystitis associated with O. viverrini, gall bladder specimens from ninety-two patients who had undergone cholecystectomy at the Khon Kaen Regional Hospital, Khon Kaen, Thailand. Two representative sections from the body of fresh gall bladder tissue were fixed in Carnoy's solution and embedded in paraffin wax. The paraffin sections were stained for mast cells and IgE plasma cells by the double histochemical and immunohistochemical method. The cells in the epithelium, lamina propria, muscular layer, and subserosa were counted and expressed as cells per square millimeter. The gall bladder bile was examined for the presence of O. viverrini eggs. Significantly higher mean mast cell numbers were found in the lamina propria (221.41 ± 16.01 vs 116.97 ± 14.61 cells per mm²; P < 0.005) of egg positive compared to egg negative groups, respectively. No comparable differences in mast cell number were observed in other layers. IgE plasma cells were rarely seen. The results suggest that mast cell hyperplasia occurs during cholecystitis in association with opisthorchiasis and may play a role in the pathogenesis of the disease.

Subsets of migrating intestinal dendritic cells

Dendritic cells (DCs) in the intestine are heterogeneous. Phenotypically different populations of conventional DCs have been identified in the intestinal lamina propria, Peyer's patches, and in the draining mesenteric lymph nodes, to which these DCs constitutively migrate. Markers used to identify these populations include major histocompatibility complex class II, CD11c, CD8 alpha, CD11b, and CD103. Extensive studies in rats, summarized here, which involved collection of migrating DCs by thoracic duct cannulation after mesenteric lymphadenectomy, have clearly demonstrated that the subsets of migrating intestinal lymph DCs have different functional properties. The subsets might play different roles in the induction of oral tolerance and in driving systemic immune responses after vaccination or intestinal stimulation with Toll-like receptor ligands. The use of these surgical techniques allows investigation of the functions of purified subsets of migrating DCs. However, in the rat, these studies are limited by the range of available reagents and are difficult to compare with data from other species in this fast-moving field. Recent refinements have enabled the collection of migrating intestinal DCs from mice; our initial results are described here. We believe that these studies will generate exciting data and have the potential to resolve important questions about the functions of migrating intestinal DC subsets.

Prospects for the immunological control of ruminant gastrointestinal nematodes: natural immunity, can it be harnessed?

Current understanding of the mucosal immune response to nematode parasites is briefly reviewed with emphasis on the role of the cytokines interleukins-4 and -12 and gamma interferon (IFN gamma) in the development of T-helper responses in rodents. Data from laboratory animals and ruminants indicate that the events associated with a T-helper 2 (Th2) cell response, notably IgE synthesis, eosinophilia and mucosal mastocytosis are protective. Evidence that effector mechanisms may vary for different parasite species is considered. Current gaps in understanding such as the location in the gut and mechanism of antigen processing and presentation as well as the relative contribution of non-immunological effector responses, such as gut motility and mucus secretion, to worm expulsion are discussed.

IgE antibody-forming cells in rats infected with Nippostrongylus brasiliensis and immunized with antigens

The distribution of IgE antibody-forming cells was examined in rats infected with Nippostrongylus brasiliensis (Nb) or immunized with Nb antigen or with OA. The frequency of antigen-specific IgE antibody-forming cells was detected by a passive cutaneous anaphylactic (PCA) reaction using cell extract from lymphoid organs. In Nb-infected rats, anti-Nb and anti-4th stage larvae (L4) IgE-forming cells distributed mainly in the mesenteric and the bronchial lymph nodes (LN) near the parasite-harboring sites. After intraperitoneal (ip) immunization with Nb antigen mixed with Al(OH)3 and Bordetella pertussis (Bp) as adjuvants, anti-Nb IgE antibody-forming cells were detected in the mesenteric and the bronchial LN. Anti-Nb or OA IgE antibody-forming cells after subcutaneous (sc) immunization were found in the inguinal and the axillary LN. An effect of Bp on the distribution of IgE antibody-forming cells seems to be ruled out. The distribution of IgG2a antibody-forming cells was similar to that of IgE antibody-forming cells, indicating that the distribution of the IgE antibody-forming cells is not preferential. IgE antibody-forming cells were stimulated in the regional LN near the site of antigen administration. IgE antibody-forming cells induced by potentiated IgE antibody production were also examined. Rats were immunized ip or sc with OA and infected with Nb. Anti-OA IgE antibody-forming cells were found in all of the lymphoid organs and especially in the regional LN near the Nb parasite-harboring and antigen administration sites.