MDSCs can suppress anti-tumor responses through several mechanisms: suppression of CD4+ and CD8+ T cells by arginine and cysteine depletion, inhibition of T cell recruitment to tumor sites, inhibition of T cell-peptide-MHC interactions, skewing of the cytokine milieu toward type 2 or regulatory responses, and modulating NK and NKT responses [3]–[13]. The gene discussed is CD4; the disease is neoplasm.