T follicular helper (TFH) cells represent a T cell subset dedicated to the activation of B cells. They have been involved in the pathogenesis of autoimmune diseases in humans such as lupus and Sjögren disease. We recently showed that TFH are implicated in the activation of autoreactive B lymphocytes during ITP. Autoimmune hemolytic anemia (AIHA) is an autoimmune disease due to antibodies targeting red blood cells. To date, the role of TFH in the pathogenesis of AIHA is not known.

We hypothesize that AIHA is associated with an increase in the number and/or function of TFH, that could participate in the activation of autoreactive B lymphocytes.

Inclusion Criteria:

• Patients with a diagnosis of warm AIHA defined by

  • Hemoglobin <11 g/dl
  • Low haptoglobin level
  • Positive direct antiglobulin test (IgG or IgG + complement)
  • Reticulocyte count >120 G/L

• Patients

  • naive to treatment for hemolytic anemia or a in relapse
  • Older than 18 years
  • Able to understand written and spoken French

• Persons who have provided written consent

Control population

• Patients who have given consent
• Patients over 18 years
• Patients with cold agglutinin disease (progressive AIHA and different treatments of warm autoantibody AIHA) can be included as a sub-group of controls
• Patients with non-auto-immune hemolytic anemia (constitutional of enzymatic origin, membrane-related,…) can be included as a sub-group of controls

Exclusion Criteria:

• Patients without national health insurance
• Pregnancy or breast-feeding women
• Adults under guardianship
• Patients with cancer or malignant hemopathy
• Patients with an on-going infection
• Patients treated with corticoids or immunosuppressants

Patients with a diagnosis of warm AIHA Patients with non-auto-immune hemolytic anemia