Neutralization of inhibitory activity derived from cells of MDS patients and ML-2 cell line by monoclonal antibodies against H and L-subunit-rich ferritins.

Monoclonal antibody 2A4 against human heart ferritin and a polyclonal antibody against human placental ferritin inactivated the suppressor activity present in media conditioned by cells of patients with myelodysplastic syndrome (MDS). These antibodies also neutralized the inhibitory activity released by cells of myeloid leukemic ML-2 cell line. In contrast, a monoclonal antibody against the ferritin L subunit did not neutralize the inhibitory activity of the media conditioned either by the cells of patients with MDS or by the ML-2 cell line. Neutralization of the inhibitory activity present in supernatants of cells of MDS patients and the ML-2 cell line by monoclonal antibodies against the H subunit of ferritin strongly indicates that the inhibitory activity resides in the acidic isoferritin molecule.