Lymphopenia may identify an immunologically distinct subset of MS, researchers report.
Patients who have lymphopenia before being treated for multiple sclerosis (MS) are likely to have lymphopenia after treatment, according to a recent retrospective controlled study. The study, conducted by Zhi Wei Lim, BM, BS, of the University of Southampton in the UK, and colleagues, was published in the journal Neurology Neuroimmunology & Neuroinflammation on August 12, 2016.
The authors say that studies regarding lymphopenia and treatment-naive MS have produced conflicting results, motivating them to conduct this retrospective study. They say, “This is important since lymphopenia may identify an immunologically distinct subset of MS,” adding that lymphopenia “may emerge as a risk factor for serious viral infections of the brain during dimethyl fumarate treatment.”
In order to investigate, the researchers collected data over a 2-year period about patients with relapsing MS. They found baseline blood test data fro 466 patients and posttreatment data for 247 patients. “Lymphocyte counts were relatively stable with time, with a coefficient of variation of 7.5%” report the researchers.
“There was no association between pretreatment lymphocyte count and any patient characteristic or month or season,” say the authors. They compared the rate of lymphopenia in the pretreatment MS patients with that of a matched population of patients who were undergoing cosmetic septoplasty and report, “There was no statistical difference in mean lymphocyte count or prevalence of lymphopenia.”
After the MS patients were treated with interferon beta, glatiramer acetate, or fingolimod, the only predictor of lymphocyte count the researchers could identify was lymphopenia before treatment, leading them to say, “the lymphopenia in patients with MS is unlikely to be related to autoimmunity,” adding, “Moreover, lymphopenia was not associated with relapsing activity.”
“We found that pretreatment lymphopenia predicts posttreatment lymphopenia; this is useful since it identifies at-risk patients needing frequent monitoring,” say the authors. They note, however, that because this was a retrospective study lymphocyte subsets were not available and suggest that future studies should address whether “lymphocyte subsets during lymphopenia differ in patients with MS vs controls.”