Homogeneous immunoglobulins following allogeneic bone marrow transplantation

Homogeneous immunoglobulins are frequently detected in the serum of patients undergoing allogeneic bone marrow transplantation (BMT). The aim of the present study was to further characterize the incidence of this phenomenon and its correlations with laboratory and clinical data. Serum samples were gathered from 29 patients undergoing allogeneic or syngeneic BMT for chronic myeloid leukemia (CML), and serial protein (IgG, IgA and IgM) quantification, electrophoresis and immunofixation were performed. Transient mono- or oligoclonal gammopathies were observed in 23 out of 29 patients between days 20 and 1,750 following transplantation. The presence of homogeneous immunoglobulins was not correlated with the following clinical parameters: graft-versus-host disease, bacterial sepsis, Epstein-Barr virus or cytomegalovirus infection or invasive fungal infection. Therefore, the development of mono- or oligoclonal immunoglobulins may represent a complex disorder of B cell regeneration which may be caused by an intrinsic B cell defect, or a failure in the regenerating T cell system, or both, manifesting itself in a restricted antibody diversity after allogeneic BMT.