SUMMARY A method for the detection of total, type I, and type II intrinsic factor antibodies was devised. The technique comprises a two-site solid phase enzyme linked immunosorbent assay (ELISA), with human intrinsic factor conjugated with horseradish peroxidase as label and attached to polystyrene tubes as solid phase. One conjugation provides sufficient material to assay more than 10 000 patient samples. The label proved stable during the course ofthis evaluation and was still in use more than 12 months after preparation. When applied to 45 serum samples from cases of pernicious anaemia, intrinsic factor antibodies were shown in 30 (67%). Simplicity, high capacity, low cost and label stability, combined with relatively high clinical sensitivity make the method suitable for cost effective screening of large numbers of samples. Simple modifications to the basic assay reagents permitted type I and type II intrinsic factor antibodies to be differentiated.Despite being available for almost 30 years,' application of tests for circulating antibodies to gastric intrinsic factor has been limited, because the tests have not been readily available to all routine laboratories, and secondly, they have been capable of showing the presence of antibodies in only about 50% of patients with pernicious anaemia. It has been proposed, however, that the demonstration of intrinsic factor antibodies in patients with megaloblastic anaemia and low serum vitamin B12 concentrations could be regarded as diagnostic ofpernicious anaemia and may avoid the need for B12 absorption tests.2Two types of intrinsic factor antibody are known to exist,3 one ofwhich reacts with the intrinsic factor-B12 binding site (type I); the other (type II) detects an antigen site unrelated to the B12 binding activity. Methods of detection have concentrated on type I, making use ofthe ability ofthe antibody to prevent the uptake of 57Co-B12 by intrinsic factor, combined with a charcoal separation procedure.' Recently, a method that used 1251-labelled intrinsic factor has been described: this focuses on the ability of the antibody to bind to intrinsic factor directly' instead of showing a type I antibody blocking effect.' This method has also been modified to detect and quantify both type I and type II antibody.89 A commercial intrinsic factor antibody method [Walker
Aims: To investigate the incidence of type II autoantibodies to intrinsic factor in pernicious anaemia. Methods: Three hundred and forty four serum samples submitted for intrinsic factor antibody (IFAB) analysis on clinical or laboratory grounds were tested by an established radioassay and a new enzyme linked immunosorbent assay (ELISA) method for type I and total IFAB, respectively. Sixty of these were found to be positive by ELISA; this method was used to test further, 40 samples of adequate volume for types I and II antibodies. Results: Type II antibodies were detected in 39 of the 40 sera tested. A comparative analysis indicated that seven samples contained pure type II antibody, being positive for total and type II by ELISA, but negative for type I by both the ELISA and radioassay technique. Conclusions: The occurrence of type II antibody, both alone and in combination with type I, seems to be more common than has previously been recognised, and emphasises the advantage of using a technique which will detect both types of antibody. ( Clin Pathol 1993;46:45-47
Aims: To determine the effect of concomitant azathioprine treatment on the response of patients with renal failure to treatment with subcutaneous recombinant human erythropoietin (r-HuEPO). Methods: Two groups of patients with renal failure not receiving haemodialysis were studied. One comprised seven patients receiving erythropoietin alone, the second consisted of nine patients who were also treated with azathioprine. The haematological changes were monitored, and the functional erythropoietic response was studied by two different ferrokinetic models. One analysed the initial, the other the extended plasma iron clearance. Studies were performed
In 16 patients (9 on azathioprine, 7 not) the ineffective iron turnover (I IT) was much higher in the azathioprine group (62.7 ± 6.7 vs. 23.5 ± 3.5 μmol/l blood/ day, p < 0.0001, 2-tailed t test), though the red cell iron turnover (ROT) was similar (42.8 ± 2.9 vs. 41 ± 4.8). Erythropoietin improved the anaemia in all patients and raised the RCIT (4 still on azathioprine to 72.2 ± 9.8, p < 0.003; 7 non-azathioprine patients to 62.7 ± 5.3, p < 0.01); the ΠT remained higher in the azathioprine-treated (85.5 ± 19.3 vs. 37.1 ± 5.4; p < 0.013). In 2 patients who discontinued azathioprine, the IIT declined markedly to normal. In summary, azathioprine exacerbates the anaemia of renal failure by augmenting ineffective erythropoiesis, while erythropoietin benefits those on azathioprine as much as other renal patients by stimulating both effective and ineffective erythropoiesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.