CD4 and myeloid sarcoma: Individuals expressing the HLA-DR15 gene product show a proportionate increase in autoreactivity of peripheral CD4+ T helper (TH) lymphocytes (Jelcic et al, 2018; Mohme et al, 2013), in agreement with the finding that HLA-DR15 haplotype confers significant genetic susceptibility to the development of MS (Attfield et al, 2022).