Biologic properties of E myeloma proteins

Abstract

E myeloma protein PS (PS protein) from the serum of the second known patient (P.S.) with IgE myeloma was purified by DEAE-cellulose column chromatography and Sephadex ® G-200 gel filtration. The physicochemical properties of this protein were identical with those of E myeloma protein ND (ND protein) from the first patient with IgE myeloma; however, double immunodiffusion studies revealed distinct idiotypic antigenic determinants probably belonging to the Fd portion of the molecule in both E myeloma proteins. Patient P.S. failed to accept passive sensitization with reaginic antibodies (the Prausnitz-Kustner reaction) and reacted only to the intradermal injections of high concentrations of antilgE (the reversed Prausnitz-Kustner reaction). He was capable of reacting normally to the intradermal injection of histamine. It is postulated that the absence of passive sensitization with reaginic antibodies was due to saturation of IgE-fixing sites of target cells with E myeloma protein. The impaired reversed Prausnitz-Kustner reaction may be explained by failure of the injected anti-IgE to react with cell-fixed IgE because of the presence of an excessive amount of E myeloma protein in extracellular fluid. Histamine release from the patient's leukocytes by treatment with anti-IgE was studied. Studies of IgE metabolism were also made, using 125I-PS protein and 131I-ND protein. The metabolic parameters of both proteins were identical, with a half-time of 5.1 days and fractional catabolic rate of 16 per cent in patient P.S., in contrast to 2.5 days and 89 per cent, respectively, in normal subjects.