Immune neutropenia associated with anti-human neutrophil antigen-2a (NB1) antibodies following unrelated donor stem cell transplantation for chronic myeloid leukaemia: perpetuation by granulocyte colony-stimulating factor.

A case of immune neutropenia following unrelated stem cell transplantation for chronic myeloid leukaemia is described. The neutropenia developed following herpes zoster viral infection and was associated with antibodies to the human neutrophil antigen (HNA)-2a (formerly known as NB1). The neutropenia was prolonged, profound and unresponsive to granulocyte colony-stimulating factor (GCSF). The neutrophil count recovered after GCSF was discontinued. HNA-2a has been reported to be upregulated following GCSF administration. In the present case, it appears that the immune neutropenia may have been perpetuated by GCSF administration.