Therefore, these costimulatory molecules in patients with histiocytic sarcoma may be affected by the systemic immune status induced by histiocytic sarcoma and may play a critical role in antitumor activity because the histiocytic sarcoma tumor tissue expresses CD86 molecules that can bind to CD28 and CTLA-4 [12]. This evidence concerns the gene CD86 and histiocytic sarcoma.