Surface localization of high-mobility group nucleosome-binding protein 2 on leukemic B cells from patients with chronic lymphocytic leukemia is related to secondary autoimmune hemolytic anemia

MORANDE P; BORGE M; ABREU C; GALLETT J; ZANETTI S; NANNINI P; BEZARES RF; PANTANO S.; DIGHIERO G; OPPEZZO P; GAMBERALE R; GIORDANO M

LEUKEMIA AND LYMPHOMA

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2015 vol. 21 p. 1 - 8

1042-8194

Chronic lymphocytic leukemia (CLL) is the main cause of autoimmune hemolytic anemia (AHA). However, the cellular basis underlying this strong association remains unclear. We previously demonstrated that leukemic B cells from patients with CLL recognize the erythrocyte protein Band 3, a prevalent autoantigen in AHA. Here we show that the major binding site of Band 3 on leukemic cells is an extrinsic protein identified as high-mobility group nucleosome binding protein 2 (HMGN2), a nucleosome-interacting factor which has not been previously reported at the cell surface. T lymphocytes do not express HMGN2 or bind Band 3. Removal of HMGN2 from the cell membrane abrogated the capacity of Band 3-pulsed CLL cells to induce CD4 + T cell proliferation. We conclude that surface HMGN2 in leukemic B cells is involved in Band 3 binding, uptake and presentation to CD4 + T lymphocytes, and as such may favor the initiation of AHA secondary to CLL.