Plasma Protein Changes in M-proteinemic Type

Abstract

Each class of normal immunoglobulins is a more or less continuous spectrum of molecular variability, showing a characteristic electrophoretic heterogeneity. As a general rule, a single clone of the immunoglobulin-producing cells produces only a single variant of heavy chain and light chain, and they are commonly called as “monoclonal immunoglobulin”. A single monoclonal immunoglobulin should be electrophoretically separated as a homogeneous, compact band or a discrete peak (Fig. 194). Monoclonal immunoglobulin is also called as M-protein, M-component, or M-fraction. At the beginning, “M” was understood to mean “myeloma” or “macroglobulinemia”.³⁰⁷⁾ However, the identical immunoglobulin has been encountered in other clinical conditions, and thus “M” denotes “monoclonal” according to Waldenström.³⁹⁹⁾ M-protein is also designated by WHO (1964) as “pathological immunoglobulin” (P.Ig), and defined as “abnormally homogeneous populations of immunoglobulin molecules”.³³⁸⁾