To the Editor With interest we read the article by Frohman and coauthors,1 contrasting our own findings. As previously reported, we failed to detect JC virus (JCV) DNA in peripheral mononuclear cells (PBMCs), CD34+ hematoprogenitors, and bone marrow.2,3 We might have missed the low levels of JCV DNA reported by Frohman and coauthors owing to an 8-fold-lower total blood volume available in our study.2 Recently, another study confirmed the observation of JCV DNA in PBMCs, including the CD34+ subset,4 favoring PBMCs as a reservoir for JCV. Nevertheless, to our understanding, it remains unclear whether PBMCs or CD34+ cells represent a relevant reservoir.
Warnke C, Adams O, Kieseier B. Relevance of CD34+ Cells as a Reservoir for JC Virus in Patients With Multiple Sclerosis. JAMA Neurol. 2014;71(9):1192. doi:10.1001/jamaneurol.2014.1855