Antibodies reactive with neutrophils following allogeneic haematopoietic stem cell transplantation

Allogeneic haematopoietic stem cell transplants might induce immunological alterations leading to autoimmune-like syndromes. In particular neutrophil- associated antigens could represent the target for autoantibodies against n eutrophils in patients receiving an allogeneic peripheral stem cell or bone marrow transplantation, giving rise to granulocytopenia. With this aim we studied prospectively 43 allotransplanted patients for the presence of anti bodies reacting with neutrophils (ARN), looking for a correlation with a po st-engraftment neutropenia. Our data showed that the direct test for ARN wa s positive in 30 patients. Interestingly, 7/7 patients who received a T-cel l-depleted marrow transplant developed ARN. Antibodies with a specific neut rophil-antigen reactivity were detected in 4 patients, 1 with an anti-CD16/ Fc gamma RIIIb receptor reactivity and 3 with anti-NA1 reacting patterns, r espectively. From a clinical point of view, it was not possible to demonstr ate a close and significant relationship between neutropenia and ARN, altho ugh patients showing ARN had slightly lower absolute levels of peripheral n eutrophils until 6 months after BMT. In conclusion, ARN may be detected in the majority of patients following allogeneic stem cell transplantation; in addition, since ex vivo or in vivo T-cell-depletion leads to a higher perc entage of patients positive for ARN, it could be hypothesized that "autoimm une-Iike" disorders in transplanted patients might be related to a T-cell d erangement due to different numbers and subsets of T lymphocytes.