CLL cells express HMGN2 as a surface membrane protein: relevance in band 3 binding and AHA initiation

MORANDE PABLO; BORGE MERCEDES; NANNINI PAULA; BEZARES FERNANDO; CABREJO MARÍA; OPPEZZO PABLO; GAMBERALE ROMINA; GIORDANO MIRTA

Cologne

Workshop; FIFTEENTH INTERNATIONAL WORKSHOP ON CHRONIC LYMPHOCYTIC LEUKAEMIA; 2013

The association of chronic lymphocytic leukemia (CLL) and autoimmune hemolytic anemia (AHA) haslong been known, but the causes of this association are poorly understood. We have previouslyshown that neoplastic B cells are able to bind the erythrocyte protein band 3 (B3), the most abundantprotein in the outer membrane of red blood cells and a frequent target of autoantibodies in AHA,through its N-terminal domain (B3N). Upon B3 internalization, CD40L-activated CLL cells inducespecific T cells proliferation in a HLA-DR dependent manner. The aim of the present work was toidentify molecules in the cell membrane of leukemic B cells as candidates for being B3N binding site.Using FACS analysis, we found that removal of non-integral membrane proteins from leukemic B cellsby acidic elution decreased the binding of B3N (50 μg/ml) (MFI control cells: 171±10, MFI treatedcells: 58±12, n=5, p