Prognostically significant bone marrow cellular content changes in diffuse large B-cell lymphoma

Introduction. Increasing of blast cell percentage in bone marrow of diffuse large B-cell lymphoma patients is a sign of unfavourable prognosis. We estimated the frequency of this phenomenon and made attempts to idenify minimal bone marrow involvement in DLBCL by flow cytometry.

Materials and methods. Study has been done in 60 DLBCL patients. Diagnosis in all cases was done according to WHO (2008) criteria. Bone marrow study was done on smears (myelogram). Immunophenotypic study was done with a large panel of B-lineage monoclonal antibodies as well as kappa and lambda light chains to membrane immunoglobulins.

Results. Increase in blast cell content in bone marrow was noted in 73.3 % of DLBCL patients. That group of patients had lower surviv al. We used the following methods for identification of monoclonal B-lymphocytes: monoclonality according to membrane light immu noglobuline chains within mature B-lymphocytes and aberrancy of immunophenotype. Levels of different B-cell antigen expression – CD20, CD21, CD22, CD24. It was identified B-lymphocytes with aberrant expression of СD21.

Conclusion. The most informative methods of identification of minimal bone marrow involvement in DLBCL are estimation of clonality according to light chain expression of mature B-lymphocytes (CD45++CD20+CD5–), as well as assessement of aberrancy of CD21 expression of mature B-lymphocytes.