Intestinal Immunoglobulin A Research Articles

Effect of parenteral immunization on the intestinal immune response to Salmonella typhi Ty21a

The effects of parenteral administration of a killed typhoid vaccine on the intestinal immune response to live orally administered Salmonella typhi Ty21a in human subjects was evaluated. Priming with parenteral vaccination neither enhanced nor suppressed the subsequent specific serum and intestinal immunoglobulin A (IgA) immune responses to a booster course of live oral vaccine. Neither a single oral dose of live vaccine nor a single dose of parenteral vaccine had any measurable booster effect on the observed primary intestinal IgA response to the live oral vaccine. Two booster doses of subcutaneously administered killed typhoid vaccine did result in a significant increase in the specific intestinal IgA antibody in those subjects primed with the oral live vaccine. This response was comparable in magnitude to the primary intestinal response. No evidence of this response could be found in serum IgA, although nonsignificant rises in serum IgG were evident. Previous parenteral priming had no effect on secondary immune responses to a live oral vaccine in humans. Serum immune responses were generally found to be of little value as indicators of local intestinal immunity. This study confirmed that parenteral vaccination was only able to induce an intestinal immune response following priming with live, orally administered organisms and that multiple parenteral booster doses were necessary to induce a measurable effect on intestinal immune responses.

Local immune responses to the Campylobacter flagellin in acute Campylobacter gastrointestinal infection.

Intestinal immunoglobulin A (IgA) anti-campylobacter flagellin antibodies were measured by an enzyme-linked immunosorbent assay in patients with and without campylobacter infections. The level of fecal IgA antiflagellin antibodies was significantly higher in patients than in controls, but only 12 of 29 patients (41.4%) with a campylobacter infection had detectable IgA antibodies against flagellin (optical density, greater than or equal to 0.100). Further testing of fecal IgA antibodies from 10 patients with homologous and heterologous purified flagellins showed strain specificity in 1 patient. Cross-reactivity of fecal IgA antibodies with heterologous flagellins did not correlate with the Lior serotype of the isolate.

Antibody responses to Toxoplasma gondii in sera, intestinal secretions, and milk from orally infected mice and characterization of target antigens

Toxoplasma gondii-specific antibody responses in serum, intestinal secretions, and milk were identified with an enzyme-linked immunosorbent assay following a single oral infection of mice with strain 76K cysts of T. gondii. Immunoglobulin A (IgA) production began during week 2 of infection in serum and milk and during week 3 of infection in intestinal secretions and persisted in all three throughout the experiment (17 weeks). IgG but not IgM antibodies were detected in intestinal secretions later in the infection. Serum and milk IgG and IgM production began at the same time after infection as did the IgA response. In Western blotting (immunoblotting), intestinal IgA antibodies were shown to react with antigens comigrating with the T. gondii proteins p22, p23, p30, and p43, the 28-kilodalton antigen, and the 55- and 60-kilodalton rhoptry proteins, as recognized by specific monoclonal antibodies. Milk IgA antibodies reacted with antigens comigrating with p30 and p43. Most of the antigens recognized by IgA antibodies were also detected by IgG antibodies. IgA antibodies from all three biological samples detected the same major T. gondii antigens; thus, there was apparently no specific antibody production unique to one locality.

Combined parenteral and oral immunization results in an enhanced mucosal immunoglobulin A response to Shigella flexneri.

Achieving a vigorous secretory immunoglobulin A (IgA) response in intestinal secretions usually requires multiple doses of antigen given orally, while systemic immunity is more easily attained by parenteral immunization. This study examines the role of combined parenteral and oral immunizations to enhance the early mucosal immune response to an enteropathogen. We have used a chronically isolated intestinal-loop model in rabbits as a probe to monitor kinetically the initial (primary) local immune response to shigella lipopolysaccharide (LPS) following combinations of parenteral immunization intramuscularly (i.m.) and oral stimulation with shigellae. Predictably, effective stimulation of systemic immunity was elicited when heat-killed preparations of Shigella sp. strain X16 were given i.m., as shown by strong serum IgG and weak intestinal IgA activity to shigella LPS. A single oral dose of live Shigella sp. strain X16 given to unprimed rabbits elicited only a typical weak IgA response in intestinal secretions. However, when an i.m. dose of heat-killed shigellae was followed 1 day later by an oral dose of live Shigella sp. strain X16, a hyperstimulation of the early secretory IgA response was elicited, and the response reached levels found previously only after multiple oral administrations of live shigellae. This stimulation did not require the use of an adjuvant. At the same time, the animals receiving this combined oral and i.m. regimen had a lower IgG antishigella LPS activity in serum compared with their response after receiving parenteral antigen in adjuvant alone. These findings indicate that while a dichotomy exists between the systemic and mucosal immune responses, careful orchestration of the stimulatory events can promote a vigorous early local IgA response.

Administration of purified colonization factor antigens (CFA/I, CFA/II) of enterotoxigenic Escherichia coli to volunteers: Response to challenge with virulent enterotoxigenic Escherichia coli

Colonization factor antigens (CFAs) were administered orally to volunteers, and the mucosal immune response was assessed by measuring secretory immunoglobulin A (IgA) in saliva and intestinal secretions and by challenge with virulent enterotoxigenic Escherichia coli (ETEC). A combination of CFA/I and CFA/II (8 mg each) administered orally in four doses in milk failed to induce a mucosal IgA response and also failed to protect against challenge with CFA-positive ETEC. When CFA was administered orally (1.5 mg divided into three doses with bicarbonate) to volunteers without preexisting serum anti-CFA levels, it failed to elicit a serum IgG or intestinal secretory IgA response or to protect against challenge with virulent ETEC. The CFA is destroyed by acid gastric contents but it induced significant antibody titer rises in 8 of 11 (73%) volunteers with preexisting serum anti-CFA IgG levels after oral administration of 1 mg of CFA/I with sodium bicarbonate. Subcutaneous priming (50 μg CFA/I) did not induce a serum IgG response but, when followed by oral boosting (1 mg CFA/I in two divided doses with sodium bicarbonate), induced intestinal anti-CFA secretory IgA in 4 of 8 volunteers and protected against challenge with CFA/I-positive ETEC. These results, although preliminary, are encouraging and demonstrate that it may be possible to develop an effective oral vaccine based on soluble nonreplicating antigens such as purified CFAs.

Gut Mucosal, Salivary and Serum Antitoxic and Antibacterial Antibody Responses in Swedes after Oral Immunization with B Subunit-Whole Cell Cholera Vaccine

Gut mucosal, salivary and serum antibody responses to a new oral cholera vaccine, consisting of B subunit and whole cell vaccine (WCV), were studied in Swedish volunteers. A single immunization with a 0.5 mg dose of B subunit together with WCV (5 X 10(10) killed cholera vibrios) induced a local intestinal immunoglobulin A (IgA) antitoxin response in 4/6 (67%) vaccine recipients as evident from specific antibody titre rises in intestinal lavage fluid. A second administration of vaccine did not further enhance the intestinal immune response beyond the peak level induced by the initial immunization. Different doses of B subunit (2.5 and 0.5 mg) given together with 5 X 10(10) killed vibrios (WCV) induced antitoxin antibody responses in serum in about the same frequency, 10/13 (77%) responders versus 13/14 (93%), as well as in saliva, 7/13 (54%) versus 9/14 (64%), and a single immunization was almost as efficient as two vaccine administrations. Single or repeated oral vaccination only irregularly resulted in modest antibacterial titre rises in serum (9/27 = 33%) or saliva (12/27 = 44%), but stimulated a significant mucosal antibacterial response in intestine of 5/6 (83%) examined volunteers.

Increase in the Population of Duodenal Immunoglobulin A Plasmocytes in Axenic Mice Associated with Different Living or Dead Bacterial Strains of Intestinal Origin

Various bacterial strains were tested for their ability to stimulate immunoglobulin A (IgA) plasmocytes to populate the duodenal lamina propria in axenic mice. The mice were associated with the strains for at least 4 weeks. The strains inhabiting the conventional mouse intestine and belonging to the genera Lactobacillus, Streptococcus, Eubacterium, Actinobacillus, Micrococcus, Corynebacterium, and Clostridium (including the extremely oxygen-sensitive ones) are only slightly or nonimmunogenic, whereas the strains belonging to the genera Bacteroides and Escherichia have an immunogenic effect. The same result was obtained with Bacteroides and Escherichia strains isolated from the digestive tract of other animal species. The kinetics of appearance of intestinal IgA plasmocytes are similar in axenic mice monoassociated with a stimulatory strain and in conventional mice. The association of two or more strains with axenic mice leads either to the same or a greater number of duodenal IgA plasmocytes as that obtained with the most stimulatory strain monoassociated with axenic mice. The maximum stimulation recorded in all of these trials represents about two-thirds of that observed in conventional mice and was obtained in the duodenum of gnotoxenic mice harboring four bacterial strains isolated from the conventional mouse microflora. The orally administered killed cells of two immunogenic strains, E. coli and Bacteroides sp., are as immunogenic as the living cells, provided that their concentration in the digestive tract is sufficient.

Studies on Human Intestinal Immunoglobulin A

Immunoglobulins contained in the secretions of the human large and small intestine have been studied immunologically. Immunoglobulin A (IgA) in these fluids was found to share immunological characteristics previously described for salivary and colostral IgA. Antigenic determinants were present on the intestinal IgA molecule which reacted with antisera specific for secretory piece derived from saliva and colostrum. Conversely, antisera made specific for secretory piece of intestinal IgA showed reactions of identity with colostral and salivary secretory piece. In density gradient ultracentrifugation, intestinal fluid IgA was distributed in both the 11 S and 7 S regions. When segments of intestine obtained at surgery were perfused with tissue culture media and oxygenated red blood cells via associated vessels, nonsecretory IgA, much of it polymeric, was found in the effluent fluid of the perfused organ. Both 11 S secretory and 7 S nonsecretory IgA were detected in the luminal fluid of the organ. Incorporation of 14C-amino acids into IgA and secretory piece was demonstrated in perfused intestinal segments by radioimmunoelectrophoresis and radioimmunodiffusion, and significant amounts of radiopositive nonsecretory IgA entered the venous phase of the perused organs. The intestinal lamina propria may constitute an important source of circulating IgA in man, although the exact proportion of total serum IgA synthesized in secretory sites has not been delineated.