Beta-2-microglobulin in trophoblastic disease

Beta-2-microglobulin (BMG) is physically linked to the allo-antigenic HLA chain on the cell surface and is accordingly a marker for the HLA antigens. BMG concentrations were measured in serum and cerebrospinal fluid (CSF) samples from 22 patients with choriocarcinoma, 5 with hydatidiform mole and 17 reference subjects in the first trimester of pregnancy. Serum BMG levels were elevated in the patients with choriocarcinoma, particularly when human chorionic gonadotrophin levels were higher than 50 000 U/l (< 50 000 U/l - 1.6 ± 0.3 mg/l; > 50 000 U/l - 2.75 ± 0.72 mg/l; molar pregnancy - 1.42 ± 0.44 mg/l; reference subjects - 1.47 ± 0.15 mg/l) (mean ± 1 SD). BMG levels in the serum and CSF were not increased when metastases were present in the cranium. None of the patients had evidence of abnormal renal function as determined by serum urea, electrolyte and creatinine levels and the creatinine clearance rate. These results suggest that BMG and HLA antigens are expressed on the trophoblastic cells in choriocarcinoma, or alternatively that the maternal immunocytes produce increased quantities of BMG.