Effects of plasmapheresis on the plasma concentration of proteins used to monitor the disease process in multiple myeloma.

We studied the influence of plasmapheresis on the plasma concentrations of proteins (IgG, IgA, beta 2-microglobulin) used for estimation of tumour cell mass in patients with multiple myeloma. Simultaneously, the effects of plasmapheresis on plasma concentrations of proteins (CRP, alpha 1-antitrypsin, haptoglobin) used for the assessment of inflammatory processes were studied. Also, changes in the plasma concentration of protein HC, a recently described protein occurring both as a free protein and as an IgA complex, were studied. The influence of plasmapheresis varied for the different proteins. The plasma levels of IgG, IgA, CRP, alpha 1-antitrypsin, and haptoglobin decreased during plasmapheresis. The simultaneous reduction of the level of protein HC was smaller than that of IgG, IgA and haptoglobin. The plasma concentration of beta 2-microglobulin did not decrease during plasmapheresis. The recovery rates of the proteins were found to be approximately inversely related to their molecular weights.