ABNORMALITIES OF MEMBRANE-PROTEIN COMPOSITION IN PATIENTS WITH AUTOIMMUNE HEMOLYTIC-ANEMIA

Acquired abnormalities of red cell membrane protein composition in 37 patients with a positive direct antiglobulin test have been studied: 1 7 patients had true autoimmune haemolytic anaemia and 20 were HIV-infe cted subjects with a positive direct antiglobulin test but without sig ns of haemolysis, The study was carried out by performing sodium dodec yl sulphate polyacrylamide gel electrophoresis of ghost proteins follo wed by densitometric evaluation of the areas under the peaks, normaliz ed by the total (alpha+beta) spectrin content. Results show a signific ant decrease of bands 3, 4.1 and 4.2 over spectrin in patients with au toimmune haemolysis as compared to controls; at least in a small subse t of patients, different specificities recognized by autoantibodies do not seem to account for these abnormalities which are reproducible in dependently from the molecular size of bands immunoprecipitated by aut o-antibodies. A similar decrease of protein 4.2 but not of band 3 stai ning intensity is also noticeable in HIV patients with a positive dire ct antiglobulin test, These results are consistent with the hypothesis that, following interactions between autoantibodies and autoantigens, modifications occur on membrane proteins resembling a variety of quan titative defects described in inherited haemolytic anaemias, and mainl y the 'vertical interaction defects' of hereditary spherocytosis. More over, the decrease of band 3 staining intensity seems to represent a f eature of patients with immune mediated haemolysis and not only with a utoantibody binding.