Among liquid tumor cell lines, the data revealed that all cell lines such as histiocytic lymphoma (monocyte) U937 cells could acquire HLA‐G protein from autologous HLA‐G‐transfected U937 (U937‐HLA‐G) and allogeneic HLA‐G‐transfected LCL‐721.221 cells (LCL‐HLA‐G1). The gene discussed is HLA-G; the disease is reticulum cell sarcoma.