Abnormal Plasma Proteins

Abstract

“Abnormal plasma protein” is defined as the protein that cannot be detected in normal plasma but appear in plasma only in pathological conditions. Apitz first used the term ‘paraprotein’ in 1940, with the meaning of abnormal proteins not found in normal plasma. However, Apitz used the term in relation to pathological immunoglobulins found in cases of multiple myeloma, and in accord with this meaning, Wuhrmann and Wunderly classified plasma protein abnormalities into (1) dysproteinemia and (2) paraproteinemia.⁴¹³⁾ The former indicates a quantitative abnormality, while the latter a qualitative one. Subsequent to this, in Japan, the term ‘paraproteinemia’ has become widely used, being understood to mean principally the appearance of pathological immunoglobulins in blood. Since pathological immunoglobulins found in myeloma and other monoclonal immunoglobulinopathies cannot be proven to be absolutely non-existent in normal plasma, the use of the term “abnormal proteins” itself has been criticized. For instance, Walden-Ström and others have never used the term ‘paraproteinemia’ and there are many other investigators in aggreement with him. Since the two terms ‘paraprotein’ and ‘paraproteinemia’ have uncertain meanings, the author has chosen rather to avoid their use.