Toshihiko Taki

Alpha‐fetoprotein and human chorionic gonadotropin‐producing lung cancer

A 73‐year‐old man had primary lung cancer that produced both alphafetoprotein (AFP) and human chorionic gonadotropin (HCG). The preoperative serum AFP level of 1039 ng/ml decreased to the normal range 8 weeks after surgery. The preoperative serum HCG level of 11 mIU/ml, which temporarily decreased to the normal range after operation, soon increased thereafter. The serum HCG level decreased, however, to the normal range after postoperative mediastinal radiation therapy. During relapse, only the serum HCG level increased gradually to 26,000 mIU/ml 7 weeks before his death. The lung cancer was classified histologically as poorly differentiated adenocarcinoma. Immunohistochemically, AFP was detected in the mononuclear tumor cells of the primary tumor in the lung, and HCG was found in the giant cells of the subcarinal metastatic lymph node. The concanavalin A non‐reactive fraction rate for AFP was 81.3%, and appeared to differ from those of hepatocellular carcinoma and yolk sac tumor. Cancer 59:227–232, 1987.

Lymphocyte subsets in human thymoma studied with monoclonal antibodies

Lymphocyte subsets were investigated using OKT series monoclonal antibodies and flowcytometry in 16 cases of thymoma. From the viewpoint of lymphocyte subsets, thymoma could be divided into three types: thymus lymphocyte type, peripheral lymphocyte type, and intermediate type. In thymus lymphocyte type, the number of OKT‐6+ cells exceed that of OKT‐3+ cells, and are more than 50%. In peripheral lymphocyte type, the number of OKT‐6+ cells are less than that of OKT‐3+ cells and less than 10%. In intermediate type, OKT‐6+ cells are between 10% and 30%. These three types correlate well with the histologic features with respect to the number and distribution of lymphocytes in thymoma tissue. Lymphocytes were infiltrating abundantly and intermingled in the tumor cell nests in thymus lymphocyte type, and were infiltrating rather scantly and outside the nests in peripheral lymphocyte type.

Lactate dehydrogenase isoenzyme-1 in the mediastinal yolk sac tumor

LDH isozymes in both the serum and tumor tissues of 4 patients with mediastinal yolk sac tumors, and in the cystic content of tumors transplanted into nude mice was examined. Our findings suggested that LDH-1, along with AFP, is an important marker of this tumor, and that LDH isozyme study is necessary for its diagnosis.