Rapid protein A assay for intrinsic factor and its binding antibody

A systematic approach to the assessment of erythropoiesis

The pathogenesis of anaemia may be simple or complex and the differential diagnosis can be difficult. An appreciation of the erythropoietic processes is required, together with regular review of investigations, to ensure that appropriate protocols are adopted. The application of tests, which define different facets of erythropoiesis, should be appropriate to the clinical circumstances. In some situations, such as the anaemia of chronic disorders, pregnancy and chronic renal failure, a detailed analysis of erythropoiesis is often required. Guidelines for investigating anaemia due to megaloblastosis or haemoglobinopathy are well established, whereas disturbances of iron metabolism are often difficult to classify. These require a clear distinction between storage and functional iron to differentiate whether the defect is due to readily treatable simple iron deficiency or more complex mechanisms, which do not respond to iron supplementation. Determination of red cell haemoglobin content, reticulocyte analysis and the assay of serum transferrin receptors are new generation parameters developed to address this. Practice pressures and new treatment options have contributed to investigations becoming more complex, especially those of the secondary anaemias, as new tests have become more readily available and often automated. This has resulted in reduced turnaround times and clinical demand has driven request patterns. Initiatives to develop evidence-based anaemia management protocols are welcomed but, wherever possible, should be developed through collaboration between the haematology department and the user unit, and based on available guidelines.

High incidence of type II autoantibodies in pernicious anaemia

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.