Thymosin cannot be given after lymphoma stem cell transplantation. Thymopeptide is an immunomodulatory drug used in patients suffering from chronic hepatitis B, various primary or secondary T-cell-deficient diseases, etc. The use of thymopeptide after lymphoma stem cell transplantation may increase autoimmune rejection. Thymopeptide induces T cell maturation of T lymphocytes in the peripheral blood after mitogen activation, and increases the secretion of various lymphokines by T cells after activation of various antigens or mitogens. Thymopeptide has the effect of regulating and enhancing the immune function of human cells. For patients after stem cell transplantation who need to reduce autoimmune rejection, thymic peptide cannot be used. Therefore, thymic peptide cannot be administered after lymphoma stem cell transplantation, as prescribed by the doctor.