Biological Features of CD5+ CD19+ B1 Cell and Natural IgM (VH4-34) in Chronic Lymphocytic Leukemia vs. Multiple Sclerosis

Chronic lymphocytic leukemia (CLL) is the clonal expansion of mature CD5+ B cells and the most common lymphoproliferative disease in adults (B1-CLL). B1 cells' anti-inflammatory effects include the production of natural IgM (nIgM) by the spleen and bone marrow, decreased inflammatory cytokines as a primary response to maintaining tissue homeostasis, and enhanced release of transforming growth factor β (TGFβ). We used the flow cytometry technique in peripheral blood from patients with CLL and multiple sclerosis (MS) to immunophenotype B cells and their subpopulations. Whole blood from CLL and MS patients, as well as healthy controls, was used to detect nIgM using the VH4-34 gene copy number and real-time RT-PCR. We found that the proportion of CD5+ B cells was significantly lower in MS patients than in the control group and that CD5+ B lymphocytes were significantly higher in CLL patients than in the control group. Compared to the control group, CLL patients had significantly higher levels of the VH4-34 gene copy number. On the contrary, MS patients had significantly lower VH4-34 gene copy number levels compared to the control group. As the number of antibodies in CLL patients increases due to the high number of B1 cells, we propose a new way to treat MS by extracting this natural antibody from the sera of CLL patients and injecting it into MS patients.