Abnormal expansion of naïve B lymphocytes after unrelated cord blood transplantation - a case report

Abstract

A 33‐year‐old woman underwent unrelated cord blood transplantation (U‐CBT) for myelodysplastic syndrome (MDS)‐related secondary AML. She showed impressive increases in the number of CD19⁺ B cells in bone marrow and CD19⁺27⁻IgD⁺ B cells in peripheral blood from about 1 month to 3 months after U‐CBT. The serum level of IL‐6 temporarily increased after transplantation, and this increase seemed to be correlated with the expansion of CD19⁺ B cells. Although, compared with BMT, little is known about the kinetics of hematological and immunological reconstitution in U‐CBT, there was initial B‐cell recovery after CBT as some described. This B cell recovery may be associated with a high number of B‐cell precursors present in cord blood (CB). The phenomenon of naïve B lymphocyte expansion that we found might be associated with a high number of B‐cell precursors present in CB.