Autoimmune hemolytic anemia with predominance of IgA autoantibody

A 71-year-old woman with severe autoimmune hemolytic anemia had negative direct antiglobulin tests using commercial broad spectrum antisera. Her unwashed cells agglutinated spontaneously in the potentiating medium polyvinylpyrrolidone (PVP) solution or in hexadimethrine bromide (Polybrene) solution. A strongly positive direct antiglobulin test was obtained with specific antihuman IgA sea with or without PVP. In PVP solution, small amounts of IgG, IgM, and complement components were also detected on her cells. The findings illustrate the ability of anti-human IgA to detect autoimmune red blood cell sensitization when other immunoglobulin classes of autoantibody are below detectable levels or absent. Also illustrated is the value of PVP and Polybrene in detecting agglutination in the evaluation of "antiglobulin negative" hemolytic anemia.