Test diretto all’antiglobulina stimolato con mitogeni

Background. Direct antiglobulin test (DAT), the hallmark of autoimmune haemolytic anaemia (AIHA), can be performed with different laboratory techniques, which have variable sensitivity and/or specificity. In a minority of patients, named DAT-negative AIHA, the diagnosis is made in exclusion. We recently described a new method for the detection of anti-RBC antibodies in mitogen-stimulated whole blood cultures, named mitogen-stimulated-DAT (MS-DAT). Aim. To investigate the prevalence of MS-DAT positivity in a larger series of DAT-positive and DAT-negative AIHA at different states of disease activity, and in B-CLL with or without DAT-positive AIHA. Materials and methods. We studied 33 DAT-positive AIHA with different disease activity, 7 DAT-negative AIHA, and 69 B-CLL patients. MS-DAT was performed by stimulating whole blood cultures with mitogens, and anti-RBC antibodies were detected by competitive solid phase ELISA. Standard DAT was performed with tube test, in solid phase and with enhancing solutions. Results. MS-DAT was positive in 6 DAT-negative patients with a history of DAT-positive AIHA, who were in clinical and laboratory remission at the moment of the study, and in 7 DAT-negative haemolytic anaemias, diagnosed as autoimmune in exclusion. MS-DAT was positive in 1/3 of the B-CLL patients without haemolytic features. MS-DAT was routinely performed during the follow-up of AIHA patients, and its values correlated with the clinical course, haemolytic parameters and response to therapy. Conclusions. In the test described here mitogen stimulation seems able to disclose a latent anti-RBC autoimmunity, both in AIHA in clinical remission and in B-CLL. MS-DAT could be proposed as an additional test for the diagnosis and monitoring of AIHA, and for the screening of those pathological conditions in which anti-RBC autoimmunity is known to be potentially harmful.