THE RELATIONSHIP AMONG PLATELET-ASSOCIATED IGG, PLATELET LIFESPAN, AND RETICULOENDOTHELIAL CELL-FUNCTION

  • 1 January 1984
    • journal article
    • research article
    • Vol. 63  (6) , 1434-1438
Abstract
Platelet-associated IgG (PAIgG) was reported to be elevated in nonthrombocytopenic patients who have a normal platelet lifespan. PAIgG apparently is a nonspecific finding in these patients and not a determinant of platelet survival. The RES plays an important role in the clearance of antibody-sensitized cells. The level of PAIgG and the platelet lifespan were related to the RES function in patients with: idiopathic thrombocytopenic purpura (ITP), and 5 patients with elevated levels of PAIgG yet normal or near-normal platelet counts. RES function was assessed by measuring the clearance of autologous Cr-labeled red cells sensitized with a precise amount of alloantibody (2000-3600 molecules of IgG/cell). Eight patients with immune thrombocytopenia had significantly shortened platelet survivals (< 2-113 h). The 5 patients with elevated PAIgG, yet normal or near-normal platelet counts, all had normal autologous platelet survivals (186-222 h). These patients also had significantly impaired clearance of IgG-sensitized red cells, with an average of 85% of the infused red cells remaining in the circulation at 60 min (normal 42% .+-. 14%, n = 10). Every patient with elevated PAIgG and normal RES function had a shortened platelet lifespan. Those patients with elevated PAIgG and impaired RE function did not invariably have a shortened platelet lifespan. The PAIgG is elevated in some patients whose platelet survival is normal does not indicate that PAIgG is not biologically relevant. These patients may have RES blockade and do not clear IgG-sensitized cells.