Case Report, Red Blood Cell Autoagglutination: A laboratory challenge

Abstract

Introduction:

Red cell agglutination or autoagglutination is a phenomenon in which red blood cells clump together, forming aggregates. It is caused by the surface of the red cells being coated with antibodies.  This often occurs in cold agglutinin disease, a type of autoimmune hemolytic anemia in which people produce autoantibodies (termed cold agglutinins) [1]. Sometime may develop cold agglutinins from lymphoproliferative disorders, from infection with Mycoplasma pneumoniae or Epstein–Barr virus, or idiopathically. Cold agglutinins (CA) are monoclonal or polyclonal antibodies activated at low temperatures and lead to autoagglutination of the RBC membrane [2].  Binding of CA causes agglutination of erythrocytes and the antigen-antibody complex induces complement-mediated hemolysis. Intravascular hemolysis occurs due to direct complement mediated lysis while extravascular hemolysis is as a result of C3b coated red cell destruction by macrophages in the liver [3]. Patients show hemolytic anemia of varying degrees of severity, as well as episodes of hemoglobinuria and acrocyanosis, which arise or worsen upon exposure to low temperatures. Blood cell aggregates are counted as single cells by the automated analyzers used to run complete blood count tests [4]. This leads to a markedly decreased red blood cell count and hematocrit and markedly elevated mean cell volume and mean cell hemoglobin concentration. Red cell agglutination also interferes with routine methods for blood typing and blood compatibility testing, which rely on agglutination reactions. [5,6]