The Electrophoretic α₁-Globulin Pattern of Serum in α₁-Antitrypsin Deficiency

Abstract

Th e main constituents of the a,-fraction obtained on paper electrophoresis in a barbital buff er are 1-lipoproteins, orosomucoid (acid glycoprotein), Schmid's (1953) and Schultze et al. 's 1 -3.5 S glycoprotein (Schultze, Giillner, Heide, Schonenberger & Schwick 1955), which Schultze, Heide & Haupt (1962) recently proved to be identical with a,-antitrypsin (10)(11)(12).Th e variation, in heaIth and disease, of the a,-lipoproteins, or at least of lipids in the electrophoretic albumin- 1 region, has received fairly wide attention (for references see Lindgren & Nichols 1960) (9).Th e electrophoretic 1 -lipoprotein fraction migrates faster and spreads more, widely than most of the other components.Its electrophoretic behavior also varies with the duration of storage of the serum and with variations of the intermediary lipid metabolism.It is the heaviest normal al-component (about 300 mg per 100 ml) calculated as protein, but it is electrophoretically heterogenous and does not give rise to any well demarcated electrophoretic protein peak, which is evident on comparison of the paper and agar gel electrophoretic patterns after staining for lipids and proteins.Th e orosomucoid, which normally occurs in a concentration of about 75 mg per 100 ml (Goodman, Ramsey, Simpson & Brennan 1957) produces no demonstrable peak on paper or in agar gel electrophoresis, because it is partly masked by the slower part of the albumin fraction, and it stains only faintly with bromphenol blue (Sundblad & Wallin-Nilsson 1962) (4, 15).Th e 1x component normally occurs in a concentration of about 30 mg per 100 ml (Schultze, Heide & Haupt 1962), which is not high enough to produce a distinct peak on paper electrophoresis (11,13).Burtin (1960) has stated that the strongly antigenic 3.5 S a,-glycoprotein ( 1Z , 1 -antitrypsin) is the dominating normal 1 -component.We have accepted this concept for two reasons.Th e precipitation maximum of the line formed by anti- 1 -antitrypsin corresponds to the 1 -protein peak obtained on paper and agar gel electrophoresis with diff erent buff ers.It may be deduced from data given by Jacobson (1955) on the 1 -antitrypsin activity that if the molecular weight of the 1 -antitrypsin is about 60,000, the mean normal concentration will be 0.18 g per 100 ml.Th is amount of protein is in accord with the intensity of the relatively sharply demarcated alpha-1-band obtained on paper electrophoresis.We cannot accept Burtin's statement, based on the appearance of immunoelectrophoretic patterns, that the main al-component varies little in pathological sera.On the contrary, the 1 -antitrypsin varies considerably in disease (Jacobsson 1955), which is in accordance with the observed variations of the electrophoretic 1 -band (3).In this article we present some patients with a new type of dysproteinemia characterized by very pronounced 1 -antitrypsin defi ciency.Th e sera were revealed as abnormal on routine inspection of the paper electrophoretic strips at the laboratory since the 1 pattern had an atypical confi guration with no distinct 1 -band.Th e numerical values of the electrophoretic 1 -fractions fell within or just below the lower range of the normal variation.