Placental-like alkaline phosphatase in cancer patients determined by enzyme immunoassay (EIA) using monoclonal antibodies

239

Clinica Chimica Acta, 183 (1989) 239, 240 Elsevier

CCA 04498

Letter to the Editor

Placental-like alkaline phosphatase in cancer patients determined by enzyme immunoassay (EIA) using monoclonal antibodies Dear Editor, To reevaluate the clinical significance of placental-like alkaline phosphatase (PLAP), we prepared monoclonal antibodies against h~an placental alkaline phosphatase. Four monoclonal antibodies were obtained and were proved to react with both Regan and Nagao type alkaline phosphatase to similar extent. Other detailed characteristics of these antibodies will be reported (pers. commun.). Sera from healthy subjects and cancer patients were assayed for PLAP activity [1,2]. Cut off value was determined from mean + 2 SD of healthy subjects. Here, we

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Fig. 1. Histogram of the ~st~bution of serum PLAP activity in healthy subjects and cancer patients measured by MoAb24. Bar in each column indicates mean value. See text for details. 0009-8981/89/$03.50

0 1989 Elsevier Science Publishers B.V. (Biomedical Division)

240

described the results obtained by EIA using MoAb24 from obtained monoclonal antibodies because of its high positive ratios. The cut off value by MoAb24 was 0.049 U/l. Results were expressed by mean and positive (higher than the cut-off value) ratio for each group: healthy subjects (n = 72, 0.016 U/l, 6.9%), stomach cancer (n = 38,0.119,60%), cola-rectal cancer (n = 19,0.126 U/l, 74%), liver cancer (n = 5, 0.048 U/l, 60%), biliary tract cancer (n = 6, 0.057 U/l, 67%), breast cancer (n = 19,0.029) U/l, 32%) and lung cancer (n = 31, 0.110 U/l, 84%). Serum PLAP activity for each group was plotted in Fig. 1. In addition, serum PLAP levels were serially studied in the following two patients by this method. A patient with colon cancer (50- yr-old female) who recovered from the cancer, the high level of PLAP decreased steadily with a operation of the organ and subsequent chemotherapy. On the contrary, the other case where the patient with gastric cancer (72 yr old female) with liver metastasis, did not enough response to the treatment. The observed elevated PLAP level continued to increase even after the operation and the patient died two months after the operation. Our work indicated the assay of serum PLAP to be a possible tool to follow the pathological condition of certain cancer patients. Further studies are now in progress. Acknowledgement

We thank Drs. T. Murata and S. Akai for supplying the sera and Dr. T. Komoda for preparing the manuscript. Toyoji Sato ‘, Hiroshi Sakai ’ and Hiromichi Kuniki 3 ’ Niigaia Cancer Center Hospital, ’ Central Research Laboratory, Niishin Flour Milling Co. and 3 First Depariment of Anatomy, School of Medicine, Yamaguchi University (Japan)

References 1 McL.aughlin PJ, Gee H, Johnson PM. Placental-type alkaline phosphatase in pregnancy and malignancy plasma: specific estimation using a monoclonal antibody in an solid phase enzyme immunoassay. Clin Chim Acta 1983;130:199-209. 2 Horwich A, Tucker DF, Peckham MJ. Placental alkaline phosphatase as a tumor marker in seminoma using the H17E2 monoclonal antibody assay. Br J Cancer 1985;51:625-629.

Correspondence to: Toyoji Sate, Section Kawagishicho 2, Niigata 951, Japan.

of Clinical

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Niigata

Cancer

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