30mg partially purified pBMP was implanted into right quardriceps muscle in each rabbit. Whole blood was collected from ear veins before and after the operatin. Lymphocyte proliferation response to nonspecific mitogen PHA and to specific pBMP were measured by lymphocyte transformation test in vitro, using H—labelled thymidine incorporatcon method (~3H—TdR). The skin test and histological investigation of pBMP were also performed. It has been shown that no significant changes of cellular immunity in rabbit were observed after pBMP implantation; the immunogenicity of pBMP was weak. The likelihood of chinical use of pBMP is provided.