Electroimmunoassay of alpha-2-opsonic protein during reticuloendothelial blockade

Abstract

Physiological regulation of reticuloendothelial (RE) phagocytic activity by a plasma opsonic factor has been documented. In the recent study, serum levels of this alpha-2-opsonic protein in rats during colloid-induced RE blockade were measured utilizing an electroimmunoassay (Rocket immunoelectrophoresis) with monospecific antiserum to the purified alpha-2-glycoprotein. RE blockade was produced by the intravenous injection of the gelatinized "RE-test-lipid emulsion" at a dose of 50 mg/100 g body wt. The opsonic activity of serum at various intervals during colloid-induced RE blockade as measured by tissue slice bioassay manifested a high correlation (r = 0.98) with the serum opsonic protein concentration as measured by the electroimmunoassay. During RE blockade (30 min), there was a rapid depletion of the opsonic alpha-2-glycoprotein to 20% of the initial preinjection levels. Serum concentration of this glycoprotein remained low for at least 2-3 h after which time its concentration progressively increased with approximation of normal values by 6 h postblockade. Opsonic protein concentration at 24 h postinjection were significantly (P less than 0.05) elevated above controls. Thus, colloid-induced RE blockade is associated with the removal of this glycoprotein from the serum and recovery from RE blockade is accompanied by a restoration of opsonin levels. The electroimmunoassay can provide a sensitive technique to monitor this humoral factor known to exert a physiological control on the RE system.

Amino acid sequence of the factor XIIIa acceptor site in bovine plasma fibronectin

“…The requirement for fibronectin in the opsonization of foreign particulate matter [36] by the reticuloendothelial system and the suggested involvement of transglutaminases in receptor-mediated endocytosis [37] raise the question whether the Gln-residue in position 3 in fibronectin have a specific function in connection with the transport of fibronectin-coated particles through membranes.…”

Normal Fibronectin Levels as a Function of Age in the Pediatric Population

“…In animal studies, RES function in vivo is correlated with fibronectin levels and associated opsonic activity (2,4,13). That the RES functional clearance capacity in vivo could parallel these fibronectin levels in patients can only be inferred.…”

“…In the present study, in order to complete the large number of determinations in duplicate with parallel comparisons of two different assays, serum was collected for analysis because it could be frozen to allow for assay in groups at the same time. Fibronectin levels in serum are lower than plasma, but serum can be stored at -16OC with confidence as to stability of the antigen for determinations by immunoassay (2,14). Blood was allowed to clot for one hour at 2S°C.…”

“…For the electroimmunoassay, the fibronectin was isolated from normal human serum by affinity chromatography using gelatin-sepharose, and antiserum was developed in rabbits and rendered monospecific as previously described (1, 2). The details for execution of both the electroimmunoassay as well as the immunoturbidimetric assay have been previously described in detail (2,14,15,16). The levels observed were grouped by age using the following age groups: 1-4 months (n = 14); 5-8 months (n = 7); 9-12 months (n = 11); 1-3 years (n = 17); 3-5 years (n = 19); 5-8 years (n = 21); 8-1 1 years (n = 19); and 11-15 years (n = 6).…”

Mechanism of acute depletion of plasma fibronectin following thermal injury in rats. Appearance of a gelatinlike ligand in plasma.

“…All assays were corrected for dilution by the anticoagulant. Antiserum specific for rat albumin was purchased commercially (Cappel Laboratories, Cochranville, PA), while monospecific antiserum to rat plasma fibronectin was developed in rabbits as previously described (17). Purified rat albumin and rat plasma fibronectin served as standards for the electroimmunoassay techniques as described by Laurell (18) and previously used by Blumenstock et al (17) for quantification of plasma fibronectin in rats.…”