[Isoelectric spectrum of IgD in myeloma].

Isolated and highly purified myeloma IgD DEK, STA and SAR were subjected to isoelectric focusing in thin layer of polyacrylamide gel using equipment and PAG plate 3, 5-10 from LKB. Although homogeneous in electrophoresis on cellulose acetate folien, immunoelectrophoresis and DISC PAA gel electrophoresis analysed IgD showed high isoelectric heterogeneity. They formed isoelectric spectra with 24-27 pl zonnes ower the pH range 5,4-9,3. Based on densitometric analysis of gel stripps zonnes with a small protein content were excluded from calculation of the real isoelectrical range. According to that manipulation isoelectrical range was determined as pH 6-8. Heterogeneity of isolated myeloma IgD may be due to the post-synthetic transformation of molecules in vivo as well to degradation and/or aggregation of IgD in vitro during the preparation of samples for isoelectrofocusing. However, myeloma IgD are in fact more heterogeneous in isoelectrofocusing than myeloma immunoglobulins of other classes.