Quantitative thin-layer gel filtration applied to gamma-globulin preparations

Some characteristics of aggregates of IgG and plasma proteins in heat-treated factor VIII concentrates

Eight batches of commercial heat-treated and one untreated factor VIII concentrate from 6 producers were analyzed for their content of IgG, IgG subclasses, IgG aggregates and the presence of other plasma proteins combined with the IgG as well as for anticomplement activity. Methods used were thin-layer gel filtration, immuno-gel filtration, spot immuno-precipitate assay in a double antibody version and an agarose plate haemolysis inhibition assay of complement fixation. The IgG content varied from 0.1-6.90 g/l. In all preparations IgG existed as monomers and aggregates. Associated with the IgG were also found, at significantly increased amounts compared to normal serum and intravenous immunoglobulin, one to four of the following plasma proteins; fibronectin, fibrinogen, von Willebrand factor antigen, Clq, albumin and IgA. Three batches from two producers had high anticomplementary activity, presumably caused by the IgG aggregates. Two of these deviated strikingly from normal human serum pools in percent distribution of IgG subclasses. It is hypothesized that these aggregates can induce side effects or cause immunological aberrations.

1040 prophylactic infusions with an unmodified intravenous immunoglobulin product causing few side-effects in patients with antibody deficiency syndromes

Thirty-two patients with common variable immunodeficiency (CVID) and two patients with IgA and IgG subclass deficiency received a total of 1,040 intravenous (i.v.) infusions during 60 patient years with 7,575 g of a new immunoglobulin (Ig) preparation. The content of prekallikrein activators and the anti-complementary activity in the tested Ig preparation was low and, in comparison to seven other commercial i.v. Igs, so was the proportion of IgG polymers and fragments. The IgA content was always less than or equal to 0.02 g/l, often less than 0.004 g/l, and it was possible to continuously give the Ig prophylactically to four patients with anti-IgA antibodies, i.e. three with CVID and one with combined IgA-IgG2 deficiency. Adverse reactions were only noted in 4.7% of the 1,040 infusions and in 12 out of the 34 patients. None of the reactions were of the anaphylactic type, but two patients had moderate reactions and one had anuria, probably not caused by the Ig. A simultaneous infection seemed to increase the risk of phlogistic reactions, as five out of six patients who reacted with temperature rise and chills had a simultaneous upper respiratory tract infection. A substudy of various dosage schedules was performed with 11 patients receiving 203 infusions over 10.8 patient years. On 25 mg/kg/week of Ig given i.v. every five weeks, a mean increase in the preinfusion serum IgG level of 0.3 g/l was observed, as compared to earlier i.m. prophylaxis with the same dose. Only 1/4 of the patients on 25 mg/kg/week every five or three weeks reached a preinfusion IgG level greater than or equal to 3 g/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Spot immunoprecipitate assay in gel compared with immune reactions in solution and applied to antibody titration

Precipitation profiles of spot immunoprecipitate assay (SIA) reactions in gel are shown to have characteristics analogous to classic precipitin curves representing such immune reactions in solution. Thus SIA profiles of precipitated human albumin (HSA) and anti-HSA as checkerboard analysis permit: (1) determination of optimal proportions of antibody and antigen, (2) titration of antiserum as to antigen-binding capacity and (3) estimation of the concentration of specific antibody in an antiserum. The validity of the method was confirmed by similar results already reported for precipitin analysis of anti-HSA in solution. The stained protein assay method for determination of total protein used for the calculations had a reliable (r = 0.9979) working range for quantification between 0.1 and 0.83 microgram protein in 3 microliters samples (greater than or equal to 0.03 g/l). Study of SIA profiles in the extreme antibody excess region confirmed the validity of SIA quantification. The high sensitivity of SIA as compared with radial immunodiffusion is related to high ratios (8-9) of antibody to antigen; the reliable detection limit for SIA is 10 mg/l in a 3 microliters sample. SIA is easy to perform with simple laboratory equipment, allows measurement of any precipitable antigen with very small amounts of reactants, and gives results within an hour.

A Clq immunosorbent assay compared with thin-layer gel filtration for measuring IgG aggregates

A new sensitive technique measures C1q-binding of human IgG aggregates. The method is based on the principle of the enzyme-linked immunosorbent assay with C1q-coated tubes. The IgG aggregates attaching to this C1q are shown by enzyme-linked anti-human IgG. Less than 0.01 mug of aggregates per milliliter of sample can be detected. The results with this new method showed significant correlation (P less than 0.01; Spearman rank correlation test) with the estimates of IgG aggregates of 13S or more and 10S in size obtained by thin-layer gel filtration. Both of these methods showed significant correlation with the classic hemolysis inhibition method for measuring complement fixation.

A simple numerical method for the construction of isokinetic sucrose density gradients, and their application to the characterisation of immunoglobulin complexes

A simple numerical method for calculating the parameters required for the production of isokinetic sucrose density gradients is described. Calculation is based on tables of viscosity and density of sucrose solutions at various concentrations. When density gradients prepared according to this method were used for centrifugation of a number of well characterised proteins, it was shown that isokinetic behavior occurs, and that sedimentation coefficients obtained are comparable to those determined by conventional analytical ultracentrifugation. The method was used to characterise polymers of IgM and IgG, and results suggest that IgM polymers up to the tetramer can occur in Waldenstrom's macroglobulinaemic serum, and that IgG polymers up to the pentamer can occur in stored specimens of ethanol precipitated human IgG. The sedimentation behaviour of 125I-IgE was studied by fractionating the gradients and counting the fractions, and it was shown that degradation of the labelled IgE took place during storage. It was also found that labelled IgE induces rapid breakdown of IgG with which it was mixed prior to centrifugation. The method has also been used to study immunoglobulin-containing complexes found in the knee joint fluids of patients with rheumatoid arthritis. The high degree of resolution of this method is demonstrated by the fact that many more of these components were detectable by density gradient centrifugation than by conventional analytical ultracentrifugation.

IgA in commercial gamma-globulin preparations

The presence of anti-IgA has been related to adverse reactions to injection or infusion of IgA-containing material. In this study IgA was demonstrated in all of the investigated commercial gamma-globulin preparations. In the material from a few producers it was, however, very low. By immuno-gel filtration it could be shown that the IgA consisted of aggregates as well as a 7S component and fragments. By immunoelectrophoresis-immunofluorescence IgG-IgA complexes could also be detected. The IgA aggregates could be almost completely degraded by reduction-alkylation. It is implied that such changed IgA in gamma-globulin preparations for injection may increase the risk of immunization against IgA.

Estimation of aggregates of IgG and their effect on quantitation of IgG. I. A comparison of four quantitating methods

Four quantitating techniques - radial immunodiffusion (RID),electroimmunoassay (EIA), thin-layer Sephadex gel filtration (GF), and GF with an added, specific immunoprecipitation step, immuno-gel filtration (IGF) - are compared for their accuracy in quantitating IgG of various molecular sizes - that is, pure 7S IgG and aggregated IgG, from large polymers to dimeric 10S molecular size. The aggregate fractions differed and were stable with regard to their migration in thin-layer gel filtration, their electromobility in agar and agarose, and their diffusibility in agarose. All four methods quantitated the largest aggregates four to five-fold lower and the next largest at no better than half the Lowry ratings. Only GF and IGF quantitated the two fractions of smaller aggregates within 10% of the expected value. The presence of about 50% of the two larger aggregates in prepared mixes with 7S IgG reduced quantitation results by about half to two thirds with all four methods; the smaller aggregates at 50% concentration were estimated within 16% of the correct values. Twenty percent aggragated IgG about the mean amount found in commercial gamma-globulin preparations, influenced measurments with RID, GF and IGF by less than 10% and the results with EIA by less than 16%.