Bone marrow acid phosphatase by radioimmunoassay: 3 years of experience

Clinical followup of 112 patients staged by the immunochemical determination of prostatic acid phosphatase from bone marrow aspirates is presented. This represents a 94 per cent (112 of 118) retrieval rate of a group studied more than 2 years previously. Of the 11 patients judged to be at high risk 4 (36 per cent) have suffered bony metastases, whereas only 3 of 86 patients (3 per cent) with normal bone marrow acid phosphatase by radioimmunoassay have done so. An additional 184 patients with carcinoma and 77 controls have been studied. Although radioimmunoassay greatly improves specificity in bone marrow aspirates a few falsely positive results can occur. This finding may be secondary to cross reaction from leukocyte acid phosphatase and/or interference from lipid.