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Biomedical subjects

A S Akerlund

Publications and source records attributed to A S Akerlund.

9 recordsLinked to original sources

Secretory IgA antibodies to enterobacterial virulence antigens: their induction and possible relevance.

1) Milk and salivary s-IgA antibodies are via the homing of IgA producing cells from the Peyer's patches closely connected with antigenic stimuli in the intestine. This explains the presence in human milk of s-IgA antibodies against E. coli O and K antigens, V. cholerae and Shigella O antigens, E. coli and V. cholerae enterotoxins. These secretory antibodies can be induced by intestinal exposure and boosted by parenteral vaccination. 2) Preliminary data suggest that the IgA response in the urinary tract and possibly in the lung may be involved in the homing mechanism as well. 3) The protective role of the milk s-IgA antibodies to enterobacterial virulence antigens is strongly suggested, as is the protection mediated by urinary antibodies against urinary tract infections.

Animals↗

New knowledge in human milk immunoglobulin.

One of the anti-infection principles of maternal milk is the predominant milk immunoglobulin, secretory IgA. This immunoglobulin contains antibodies against many pathogens and potential pathogens, viruses as well as bacteria, including several members of Enterobacteriacae. The antigenic stimuli for these milk antibodies seem to take place in the Peyer's patches of the intestine. Lymphoid cells leaving the patches after antigenic exposure seem to home to the mammary glands via the lymph and blood circulation. As a result, the milk contains secretory IgA antibodies against, among other things, the intestinal bacteria of the mother. These milk antibodies might reflect the spectrum of bacteria and viruses in the community and may be important for the protection of the breast-fed baby. Via the same homing mechanism the maternal milk obtains antibodies against dietary antigens, including cow's milk proteins. Studies of infants on mixed feeding suggest that the secretory IgA antibodies against the bovine proteins diminish the antigenic exposure, indicating the possibility of an anti-allergic mechanism.

Antibody Formation↗

Urinary tract infections caused by Proteus mirabilis in children. The antibody response to O and H antigens and Tamm-Horsfall protein and bacterial adherence to uro-epithelium.

Sera from seven girls with acute symptomatic pyelonephritis and nine children with acute symptomatic cystitis caused by Proteus mirabilis were analysed for antibodies against the bacterial O and H1 antigens and the Tamm-Horsfall protein. An increase in antibody levels against O antigen and Tamm-Horsfall protein was noted only in patients with acute pyelonephritis indicating that antibody determinations can be useful in differentiating between upper and lower urinary tract infection caused by Proteus in similarity to those caused by E. coli. In contrast no difference in adhesive ability was noted comparing Proteus strains causing acute pyelonephritis or cystitis.

Acute Disease↗

Protection against experimental Proteus mirabilis pyelonephritis in rats and significance of immunity.

Intraperitoneal immunization with formalin-killed bacteria as well as previous hematogenous infection with Proteus O3H1 showed a protective effect against hematogenous pyelonephritis in rats when the homologous strain was used. Transfer of hyperimmune antisera protected against hematogenously induced infection. Neither intravesical or intraperitoneal immunization with formalin-killed bacteria nor transfer of urines containing antibodies of the IgG class protected against ascending pyelonephritis when the O3H1 strain was used. Data are presented indicating that a rise of pH might decrease the biological effect of antibodies, suggesting that Proteus urease activity is a virulence factor of importance in this context.

Animals↗

A sensitive method for specific quantitation of secretory IgA.

A method to quantitate specifically secretory IgA (SIgA) has been developed using the enzyme-linked immunosorbent assay. The IgA in the test sample was adsorbed to anti-alpha antibodies attached to plastic tubes via a cost of IgA myeloma protein. The reacted SIgA was determined using anti-secretory component antiserum conjugated with alkaline phosphatase. The technique permitted quantitation of secretory IgA in biological fluids like milk, urine, and saliva with a reproducibility of +/-7%, down to 0.03 mg/l. In contrast to earlier techniques, the presence of up to 157% of serum IgA without secretory component (SC) and free SC did not disturb the measurements of SIgA. Furthermore, variations in pH and osmolarity, within biological ranges in secretions, did not influence the estimations.

Animals↗

Intestinal stimulation of the serum antibody response against Escherichia coli O83 antigen in healthy adults.

Ingestion of E. coli O83 bacteria preceded by intake of 2 g of NaHCO3 resulted in the bacteria appearing as a transient strain in the stool in 6 out of 11 healthy adult individuals. No rise in serum, urine or parotid fluid antibody levels against the crude O antigen from E. coli O83 bacteria could be detected using the enzyme-linked immunosorbent assay (ELISA) or the indirect haemagglutination (IHA) technique. In contrast, a serum antibody response was registered in four individuals with the ammonium sulphate precipitation (ASP) technique. The rise in antibody level was accompanied by an increase in relative average antibody avidity. Significantly lower levels of serum antibodies against the E. coli O83 and O6 antigens were recorded using the ASP technique as compared to those for O2, O4 and O75 antigens.

Adult↗

Differences in antigenicity of Escherichia coli strains isolated from patients with various forms of urinary tract infections.

The antibody amounts to crude O antigens were analyzed using the enzyme-linked immunosorbent assay (ELISA) and the indirect hemagglutination (IHA) technique in 42 sera from 6 rabbits. The rabbits were hyperimmunized with one of the WHO Escherichia coli standard strains O1, O2 or O75. In the antibody assays the O antigens were obtained from E. coli strains isolated from 15 patients with asymptomatic bacteriuria (ABU), from 3 patients with acute pyelonephritis and from the WHO E. coli strains used for the immunization. The strains from the patients belonged to serogroup O1, O2 or O75. Significantly higher IgG and IgM antibody levels were detected with the ELISA when using the O1 and O2 but not O75 antigens from the pyelonephritis and WHO standard strains than when using the antigens from the ABU strains. Using the IHA technique the O1, O2 and O75, IgG and IgM antibody titers against the antigens from the pyelonephritis and WHO standard strains were significantly higher than those against the antigens from the ABU strains. In inhibition experiments the antigens from the strains causing pyelonephritis inhibited the reaction between antigen on solid phase and antibodies in solution much more efficiently than did antigens from strains causing ABU.

Animals↗

Variable adherence to normal human urinary-tract epithelial cells of Escherichia coli strains associated with various forms of urinary-tract infection.

The ability to become attached to normal epithelial cells from the urinary tract was much greater in Escherichia coli bacteria isolated from the urine of patients with acute symptomatic pyelonephritis or cystitis than in those isolated from the urine of patients with asymptomatic bacteriuria. Attachment of the bacteria could be prevented by incubation in urine containing antibodies against the strain tested. The ability to attach to uroepithelial cells might be a virulence factor for E. coli strains which cause symptomatic urinary-tract infection.

Acute Disease↗