CELL-BOUND AUTOLOGOUS IMMUNOGLOBULIN IN ERYTHROCYTE SUBPOPULATIONS FROM PATIENTS WITH SICKLE-CELL DISEASE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 65  (5) , 1127-1133
Abstract
A parallel was demonstrated between most-dense (bouyant density) sickle erythrocyte subpopulations and most-dense aged normal red cells in the organization of membrane protein components in the intact cell. A corresponding similarity may exist between most-dense sickled red cell subpopulations and aged normal erythrocytes in the development of membrane protein components that function as receptors for autologous Ig. Autologous IgG retained by density-fractionated erythrocytes was esetimated by a non-equilibrium 125I-protein A (Staphylococcus aureus) binding assay. Most-dense sickle cell fractions contain more (2.7-fold and 1.8-fold, P < 0.005) cell-bound IgG in comparison to younger sickle erythrocyte fractions sedimenting at low density. Parallel findings were obtained after similar analyses of normal (homozygous-A) erythrocyte fractions. Detection of the presence of specific IgG was also carried out by direct binding of fluorescein isothiocyanate-conjugated anti-human IgG to density-separated red cell fractions followed by analyses of the fluorescent cell populations by flow cytometry. Results showed significantly higher levels of IgG bound to most-dense (12.1% .+-. 2.5% and 8.8% .+-. 0.5%) sickle red cell subpopulations (P < 0.005) in comparison to younger sickle erythrocyte fractions sedimenting at low densities (3.8% .+-. 0.32% and 4.7% .+-. 1.6% IgG-positive red cell subpopulation). Some of the same membrane changes that occur at about 120 days in normal red cells are also apparent in the chronologically younger (life span in vivo, 10-40 days) sickle erythrocyte. The increased retention of IgG by most-dense irreversibly sickled cell-enriched fractions in comparison to least-dense reversibly sickled cells or pre-irreversibly sickled erythrocyte fractions, suggests that alterations in the topography of the sickle cell membrane during the transformation in vivo to the most-dense irreversibly sickled cell morphology may produce the unmasking of cryptic antigenic sites. Opsonization of specific erythrocyte subpopulations may play a role in the pathophysiology of sickle cell disease.