Abstract
A modified enzyme-linked immunosorbent assay (ELISA) technique has been developed for the detection of secretory immunoglobulin A (SIgA) antibodies against Entamoeba histolytica. By substituting phosphate-buffered saline-Triton for phosphate-buffered saline-Tween as the antibody incubating buffer, unspecific absorption of SIgA was avoided. As revealed by chessboard titrations, the optimal amount of antigen for coating was higher in SIgA than in IgG ELISA. A purified antigen from the membrane pellet fraction of E. histolytica gave equally good reactivity with SIgA and IgG antibodies and was used throughout. A total of 283 milk and 232 serum samples from three areas in Kenya were tested. The samples were collected in maternity hospitals on one of days 1 to 3 after parturition. All milk samples were tested for total SIgA. In one of the study areas (Machakos), the mean level of SIgA was significantly lower than in the other two areas (Mombasa and Nairobi). Eighty-seven of the milk samples (31%) were reactive in the test. The rate of positives was higher in Mombasa, where the SIgA levels were highest. Since both the frequency and the level of serum antibodies were similar in the three study areas, it is likely that the higher milk reactivity in Mombasa was mainly due to the higher SIgA concentrations observed. Antibodies were detected in 32 (14%) of the sera, mostly in low or moderate titers. Surprisingly few mothers had detectable antibodies in both milk and serum. In fact, the majority of positives were reactive in either milk or serum, with a predominance of milk positives. The background for this is probably complex, containing components such as differences in immunoglobulin concentrations in the samples, diversities in local and systemic antigenic stimulation responses, and level of immunological memory.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Akerlund A. S., Hanson L. A., Ahlstedt S., Carlsson B. A sensitive method for specific quantitation of secretory IgA. Scand J Immunol. 1977;6(12):1275–1282. doi: 10.1111/j.1365-3083.1977.tb00366.x. [DOI] [PubMed] [Google Scholar]
- Diamond L. S. Techniques of axenic cultivation of Entamoeba histolytica Schaudinn, 1903 and E. histolytica-like amebae. J Parasitol. 1968 Oct;54(5):1047–1056. [PubMed] [Google Scholar]
- Ellens D. J., Gielkens A. L. A simple method for the purification of 5-aminosalicylic acid. Application of the product as substrate in enzyme-linked immunosorbent assay (ELISA). J Immunol Methods. 1980;37(3-4):325–332. doi: 10.1016/0022-1759(80)90318-x. [DOI] [PubMed] [Google Scholar]
- Gerrard J. W. Breast-feeding: second thoughts. Pediatrics. 1974 Dec;54(6):757–764. [PubMed] [Google Scholar]
- Grundy M. S. Antigen fraction from Entamoeba histolytica strain HK9 for use in ELISA. Arch Invest Med (Mex) 1982;13 (Suppl 3):249–253. [PubMed] [Google Scholar]
- Holloway P. W. A simple procedure for removal of Triton X-100 from protein samples. Anal Biochem. 1973 May;53(1):304–308. doi: 10.1016/0003-2697(73)90436-3. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Nilsson P., Bergquist N. R., Grundy M. S. A technique for preparing defined conjugates of horseradish peroxidase and immunoglobulin. J Immunol Methods. 1981;41(1):81–93. doi: 10.1016/0022-1759(81)90276-3. [DOI] [PubMed] [Google Scholar]
- Watson B. B., Lavizzo J. C. Extracellular antigens from Listeria monocytogenes. II. Cytotoxicity of hemolytic and lipolytic antigens of Listeria for cultured mouse macrophages. Infect Immun. 1973 May;7(5):753–758. doi: 10.1128/iai.7.5.753-758.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]