Alpha interferon raises serum beta-2-microglobulin in patients with multiple myeloma

Serum beta 2-microglobulin (beta 2m) levels were followed in eight patients with multiple myeloma who were treated with leucocyte alpha interferon (alpha IFN) 6 x 10(6) IU daily for 1-2 weeks before chemotherapy. Serial measurements of serum beta 2m were carried out regularly during the first week on alpha IFN. A rise in beta 2m was observed in all patients. with maximum increments ranging from 29% to 185% (mean 109%). The increase in beta 2m was most marked in patients with elevated pretreatment levels of serum beta 2m and creatinine. In six patients the peak value was reached between the third and the fifth day, after which the levels decreased. In two patients serum beta 2m remained elevated for 3 and 4 months, respectively. A marked increase in serum beta 2m can be induced by alpha IFN in myeloma, which should be taken into consideration when using beta 2m for the assessment of tumour response during alpha IFN therapy.