Citomegalovirus Serology and Response to Autologous Haematopoietic Stem Cell Transplantation in Persons With Multiple Sclerosis.

Multiple sclerosis (MS) is a prevalent autoimmune disease with increasing incidence in certain populations, and autologous haematopoietic stem cell transplantation (aHSCT) represents an important therapeutic option. Cytomegalovirus (CMV) has been implicated in the pathophysiology of several immune-mediated conditions, prompting evaluation of its potential influence on transplant outcomes. We analysed MS patients who underwent aHSCT between 2015 and 2023 with 12-month follow-up using the 'Mexican method,' assessing clinical response through the change in Expanded Disability Status Scale (EDSS) score from pre-transplant to 12 months post-procedure. Among 135 patients, 93 were classified as responders and 42 as non-responders. Lower pre-transplant EDSS was associated with a better response (p = 0.001), and women showed significantly greater improvement following aHSCT (p = 0.012). Higher serum IgG anti-CMV levels correlated with improved clinical outcomes (p = 0.021), suggesting that prior CMV exposure may be linked to enhanced response to aHSCT. These findings highlight a potential modulatory role of CMV serostatus in transplant efficacy and support the need for further studies to clarify the biological basis and clinical relevance of this association.