Secretory IgA responses in rats to antigens of various developmental stages of Nippostrongylus brasiliensis

Cohabitation in the Intestine: Interactions among Helminth Parasites, Bacterial Microbiota, and Host Immunity

Both intestinal helminth parasites and certain bacterial microbiota species have been credited with strong immunomodulatory effects. Recent studies reported that the presence of helminth infection alters the composition of the bacterial intestinal microbiota and, conversely, that the presence and composition of the bacterial microbiota affect helminth colonization and persistence within mammalian hosts. This article reviews recent findings on these reciprocal relationships, in both human populations and mouse models, at the level of potential mechanistic pathways and the implications these bear for immunomodulatory effects on allergic and autoimmune disorders. Understanding the multidirectional complex interactions among intestinal microbes, helminth parasites, and the host immune system allows for a more holistic approach when using probiotics, prebiotics, synbiotics, antibiotics, and anthelmintics, as well as when designing treatments for autoimmune and allergic conditions.

Immune response of lambs to vaccination with Ostertagia circumcincta surface antigens eliciting bile antibody responses

Immune responses to surface antigens of infective larvae of Ostertagia circumcincta recognized by bile antibodies of sheep immune to challenge were studied in 5-month-old Finn-Dorset male lambs. The sheep were vaccinated subcutaneously with 2 doses of 25 micrograms/kg body weight of surface proteins immunoprecipitated by bile antibodies derived from protected lambs. These antigens were purified from immune complexes by affinity chromatography and then injected with beryllium hydroxide as an adjuvant. The immunized lambs were challenged with 5 x 10(4) L3 and the worm burdens evaluated on day 21 post challenge. These were significantly (P < 0.01) lower in the vaccinated group than in the challenged controls (72% protection). The mucosal and bile IgM, recognizing the L3 surface, showed significantly higher levels in the vaccinated lambs compared to the challenge controls. Mucosal and bile IgA antibody levels against the same antigens were low and no significant differences were observed between vaccinated and control lambs.

Immune responses of sheep to surface antigens of infective larvae of Ostertagia circumcincta

Immune responses to surface antigens of infective larvae of Ostertagia circumcincta were studied in 5-month old Finn-Dorset male lambs. The sheep were vaccinated subcutaneously with 2 doses of 25 micrograms/kg body weight of infective larvae surface or somatic extracts and Freund's or beryllium hydroxide adjuvants. It was found that only in lambs vaccinated with L3 surface extracts and beryllium hydroxide as an adjuvant did worm burdens differ significantly (P less than 0.01) from those of challenge controls (71.7% protection). Sheep vaccinated with the same antigenic preparation but administered with Freund's adjuvant or with beryllium adjuvant and somatic extracts demonstrated rather poor protection (32.4 and 30.5% respectively). All the vaccinated sheep showed a high IgG response to L3 surface antigens while significant levels of serum and bile IgA reacting with the surface extracts were only detected in those lambs vaccinated with L3 surface extracts and beryllium hydroxide. In immunofluorescence tests serum IgA of this group reacted with the whole surface of exsheathed larvae or with the site of opening of excretory pore while IgG antibodies reacted strongly with the anterior and posterior parts of the infective larvae. Both IgA and IgG responses to surface antigens were stage specific.

Murine intestinal humoral responses in chronic Schistosoma mansoni infections

Specific and non-specific production of immunoglobulins (Ig) by the intestinal mucosa was examined in mice infected with the human blood fluke Schistosoma mansoni. Ileal and colonic mucosal tissue samples were cultured for 2 days, the medium replaced and the culture continued for a further 2 days. Ig concentrations and specific antibodies to soluble schistosome egg antigens in culture supernatants were estimated by isotype-specific ELISA. Cultured mucosae from control mice produced little IgG, but significant amounts of IgA and IgM on prolonged culture. IgG concentrations were increased in infected animals, mainly in the initial culture period, indicative of systemic, rather than local origins. By contrast, significantly increased local production of IgA and IgM occurred after the start of egg deposition in the intestinal mucosae. Although specific anti-egg antibodies of the IgG and IgM class were detected, none of the local IgA response was specific for schistosome eggs. We conclude that specific intestinal immune responses to schistosome eggs reflect systemic responses, whereas locally increased IgA production is largely non-specific. This pattern of response is likely to be related to the prior systemic exposure to schistosome eggs, which results in polyclonal local B-cell activation, but fails to trigger an antigen-specific IgA mucosal response.

Trichuris muris: antigen recognition and transfer of immunity in mice by IgA monoclonal antibodies

Mesenteric node lymphocytes from mice that had been infected with the nematode Trichuris muris, and then boosted with adult worm excretory-secretory antigens were fused with myeloma cells to produce a panel of 9 monoclonal antibodies (MoAbs). Five of the MoAbs were of the IgA isotype. The antigen recognition profiles of these MoAbs were studied using SDS-PAGE and immunoblotting; three major profile patterns were identified. Five MoAbs recognized a major band in the MW range 43-48 kD; all recognized a range of antigens. Three MoAbs were used to localize antigens in the bodies of adult worms. Granules within the anterior stichocytes were recognized strongly, as was material within the eggs and pseudocoelom. Two MoAbs stained the cuticle. Although the phosphorylcholine (PC) determinant was widely distributed within worm tissues none of the MoAbs tested recognized PC. Passive transfer of immunity was achieved using two of the IgA monoclonals; no immunity was transferred by the IgM and IgG MoAbs used. The limited recognition profiles of these IgA MoAbs, and the ability to stain stichocyte granules, suggest that their protective activity results from an interaction with ES antigens.

Aging-associated changes in murine intestinal immunoglobulin A and M secretions

The aging effect on the quantity of intestinal IgA and IgM class-specific immunoglobulins secreted and the quality of intraluminal intestinal IgA was studied in 5- to 6-month-old and 24- to 28-month-old male BALB/c mice. The level of IgA increased in the intestinal juice from the aged mice, while the IgM level remained unchanged. These alterations were similar to those found in serum, but the effect of age on serum IgA was profound, almost a threefold increase, in contrast to an increase of just under 35% in intestinal secretions. The ratio of dimeric to total IgA in the small intestine decreased in the older mice, though that of serum was unchanged. In contrast, the total amounts of dimeric IgA in the small intestinal lavage fluid did not change between the two age groups, while the dimeric IgA in serum in older mice were 4.5 times as high as those of young mice. The binding of purified intestinal dimeric IgA to antigens from normal habitant enteric bacteria (gamma streptococci and Enterobacter agglomerans) declined in the old mice. In the immunochemical studies, using SDS-PAGE and isoelectric focusing, the purified intestinal IgA from the young and old mice showed no major differences. Thus, the findings in aged small intestinal perfusates that the increased content of intraluminal IgA is due to an increased monomeric IgA, but not to a reduced dimeric IgA, which remains unchanged, and that the binding capacity of the dimeric IgA to the bacterial antigens is diminished, suggest that the level of the natural secretory IgA antibody is decreased. These altered quantitative and functional features of intraluminal intestinal IgA observed in the aged mice appear to be due to the complex heterogeneous effects of senescence on gut-associated lymphoid tissues, and may contribute to age-related impairment in gut humoral immune function.

Surface antigens of Obeliscoides cuniculi inducing local and systemic humoral responses in infected rabbits

125I-radiolabelled surface proteins of various developmental stages of Obeliscoides cuniculi were used to analyze serum and gastrointestinal immunoglobulin responses of the host to primary infection with 10,000 larvae of the nematode, using a radioimmunoprecipitation method. Serum IgM, IgA, and IgG antibodies reacted mostly with infective larval and adult nematodal surface proteins. The highest binding activity was shown by IgG against the surface of infective larvae on days 56 and 86 after infection. Local (gastric mucosal) antibodies were also predominantly directed against surface antigens of infective larvae and adults, although considerable binding of the fourth-stage larval surface proteins by gastric mucosal IgG occurred 35 days after infection. Physicochemical analysis of the radiolabelled surface antigens revealed that the strongest antigenicity was found in proteins with molecular weights of 40,000 and 145,000. Nonspecific binding demonstrated in our tests by infective larval surface proteins was associated with particles with a molecular weight of 550,000.

Local and systemic antibody responses in gerbils following vaccination with irradiated or non-irradiated Trichostrongylus colubriformis larvae

Groups of 10 Mongolian gerbils, Meriones unguiculatus, were vaccinated with 1,500 gamma-irradiated Trichostrongylus colubriformis infective larvae (L3) or with non-irradiated larvae. 25 days later five gerbils from each group were necropsied and the remaining gerbils challenged with 1,500 non-irradiated T. colubriformis infective larvae. Systemic, local intestinal and coproantibody levels were compared in each group of gerbils 25 days after vaccination and 26 days after challenge. Strong local intestinal and faecal antibody responses were detected. Coproantibodies reflected antibody levels in the intestinal contents and in mucosal extracts. The results gave further support to the view that coproantibody measurements provide a sensitive index of immunity at mucosal surfaces to intestinal parasites.