[Studies on alpha 2 macroglobulin deficiency in association with cancer metastasis]

We found 5 cases of prostatic carcinoma with metastasis with alpha 2 macroglobulin (alpha 2 M) concentration below approximately 40 mg/dl in serum. All these patients had bone metastasis, and none of them had DIC. We found no other cases with such a low concentration of alpha 2 M. Their alpha 2 M level increased to normal level after treatment with transurethral resection of prostate or hormone agents, and the level was correlated with the clinical symptom. During the clinical course, their alpha 2 M level was negatively correlated with prostate-specific antigen (PSA) and prostatic acid phosphate (PAP). All these results suggest that alpha 2 M concentration in serum reflects the severity of prostatic carcinoma with metastasis and that alpha 2 M deficiency is an indicator of metastasis. The acute phase proteins of CRP and serum amyloid A did not increase in spite of the presence of metastasis in these patients with extremely low alpha 2 M level (< 20 mg/dl), suggesting that alpha 2 M is involved in the metabolism of these acute phase proteins. On immunohistochemical studies, their specimens of prostatic carcinoma gave positive stain for PSA and urokinase-type plasminogen activator (u-PA). Both PSA and u-PA formed a complex with alpha 2 M in vitro. The alpha 2 M deficiency in these patients might be due to the complex formation between alpha 2 M and these prostate-originated proteases and to the rapid disappearance of the complex.