Direct antiglobulin test reactive with complement only in warm type autoimmune hemolytic anemia

Area of Science:

• Hematology
• Immunology
• Clinical Pathology

Background:

• The direct antiglobulin test (DAT) detects antibodies or complement bound to red blood cells.
• A positive DAT with only complement (C3) detected is an uncommon finding.
• Its clinical significance in warm autoimmune hemolytic anemia (AIHA) remains debated.

Purpose of the Study:

• To investigate the clinical significance of a direct antiglobulin test (DAT) reactive with complement (C3) alone.
• To determine the association between this laboratory finding and warm autoimmune hemolytic anemia (AIHA).

Main Methods:

• Retrospective analysis of blood bank records from 2003-2004.
• Identification of patients with positive DAT.
• Specific focus on 17 patients with DAT reactive for C3 only.
• Clinical data review for signs of hemolysis and underlying conditions.

Main Results:

• Out of 277 positive DAT cases, 17 showed C3-only reactivity.
• Nine patients had no clinical hemolysis but underlying conditions associated with autoantibodies.
• Eight patients developed AIHA, seven with severe hemolysis.
• Three patients had idiopathic AIHA; others had associated disorders (infectious, lymphoproliferative, autoimmune).
• Treatment responses varied: spontaneous resolution (2), corticosteroid therapy (3), splenectomy (3) for refractory cases.

Conclusions:

• Direct antiglobulin test (DAT) reactive with complement alone is a rare indicator.
• This finding may signify severe, refractory, and life-threatening warm autoimmune hemolytic anemia (AIHA).
• Further investigation into underlying conditions is crucial for these patients.