A New Evidence of Plasma Protein Digestion by Leukocytes

Abstract

The capacity of leukocytes to digest the plasma protein was reported in the earlier communications. It was determined by increasing NPN concentration in the medium. In the present paper this activity has been demonstrated by an evidence of the substrate consumption. The protein concentration in the system containing both blood plasma and leukocytes decreased twice as much as that in the similar system deprived of leukocytes. All electrophoretic fractions were digested, the most susceptible beeing α(2) and β globulins while the least - albumins.

The Leukocyte Digestion of Fibrinogen Degradation Products (FDP)

“…Since this kind of hydrolysis is absent in leukocyte free both blood plasma and blood hydrolysate, (1, 2), the intracellular digestion had been postulated (3,5). Recent, unpublished so far, data provided an evidence that this supposition is right (8,9).…”

“…The transport of a substrate into the leucocyte may be dependant on the molecular size and shape. Fibrinogen was not digested by leukocytes if not denaturated by chloroform (5). It is not clear whether it is the small size of the FDP molecule which enables its transportation into the cell followed by the proteolytic reaction without any denaturating reagent.…”

“…After 17 h incubation the increment of NPN in the medium was determined and considered to reflect the proteolytic activity. Other details of the procedure had been described previously (5,7).…”

“…Our previous studies have demonstrated that human leukocytes are able to digest the denaturated blood proteins (2,3,5,6). Various fractions of plasma protein as well as hemoglobin could be hydrolyzed resulting in an increase of non-protein nitrogen (NPN) concentration in the incubatory medium (5) .…”

“…Our previous studies have demonstrated that human leukocytes are able to digest the denaturated blood proteins (2,3,5,6). Various fractions of plasma protein as well as hemoglobin could be hydrolyzed resulting in an increase of non-protein nitrogen (NPN) concentration in the incubatory medium (5) . It has been postulated (2 , 3) that this phenomenon might be of some importance in vivo for elimination of the circulating protein molecules altered in a peculiar manner, because the native protein is never digested; neither is the protein denaturated by heat.…”