B lymphocytes actively participate in the pathogenesis of Multiple Sclerosis (MS). The autoantibodies produced by these cells can cause tissue damage in neurons, contributing to neurodegeneration.
B lymphocytes are more efficient antigen presenting cells when compared to other cells, since the neuroantigen is specifically recognized by the B lymphocyte antigen (BCR) receptor, processed and presented to autoreactive CD4 + T lymphocytes, also contribute to the pathogenesis of MS through the production of auto antibodies, in the presentation of neuro-antigens to CD4 + T lymphocytes and synthesis of pro-inflammatory cytokines that amplify the effective response of T lymphocytes.
Furthermore, T lymphocytes produce pro and anti-inflammatory cytokines that amplify or reduce the inflammatory response. Tertiary lymphoid tissues where B lymphocytes predominate have been described in the meninges of patients with MS in primarily progressive (EMPP) and secondarily progressive (EMSP) forms. In this study, we showed the increase in cytotoxic B lymphocytes in peripheral blood and the presence of these cells in the cerebrospinal fluid of patients with primarily progressive MS.
The increase in cytotoxic B lymphocytes is associated with an increase in the Runx3 transcription factor. In addition to the increase in cytotoxic B lymphocytes, there was a significant increase in neurofilaments in the cerebrospinal fluid of patients with PPMS and a decrease in serum levels of cerebral neurotrophic factor (BDNF).
This evidence shows that the cytotoxicity of B lymphocytes can contribute to neurodegeneration in progressive forms of MS