Immune complexes and complement in serous and mucoid otitis media

The occurrence and quantity of immune complexes in middle ear effusion (MEE) and serum, as well as serum levels of complement (C) factors were investigated in patients with chronic otitis media. Immune complexes were demonstrated in 85% of the serous MEE and in 28% of the sera. Depressed Clq values and presence of abnormal complexes, composed of subcomponents of the first C factor, indicated a disturbed function of the C system. Activation of C by the classical pathway was demonstrated in 23% of the patients. Decreased levels of properdin were also noted. The disorders within the C system tended to normalize as the otitis subsided.

Complement activation, circulating C1q binding substances and inflammatory activity in rheumatoid arthritis: relations and changes on suppression of inflammation

Patients with rheumatoid arthritis were treated with podophyllotoxin derivatives (PTD) or with cyclophosphamide. Increased concentrations of C1r-C1s-C1 inactivator complexes (C1r-C1s-C1 IA) in serum provided evidence for C1 activation, which was most pronounced before treatment. During treatment the levels of C1r-C1s-C1 IA clearly decreased, while the levels of C4 increased. This rise in C4 was contrasted to the decrease in other acute phase reactants as C-reactive protein. Circulating immune complexes were assessed by the C1q deviation test (C1q DV) and the C1 binding assay (C1q BA). Discrepancies were noted in the outcome of the two assays. Of parameters reflecting C1 inactivation C1r-C1s-C1 IA complexes were positively and C4 negatively correlated with the inflammatory activity as measured by synovitis index (SI). The values in C1q DV correlated with the C1r-C1s-C1 IA values and with SI. In contrast, C1q BA correlated with CRP but not with C1r-C1s-C1 IA or SI. The study gave evidence for a relationship between C1 activation as detected in serum and the extent of synovial inflammation in RA. The possibility is discussed that substances other than immune complexes may be involved in C1 activation and contribute to the synovial inflammation.

Complement and C1q binding substances in otitis media

Complement activation, as shown by increased amounts of complexes composed of C1r-C1s-C1 IA, and abnormal complexes of C1r-C1s were demonstrated in serum from patients with acute pneumococcal and chronic otitis media, serous or mucoid respectively. C1q binding substances were shown in middle ear effusions and in sera from patients with chronic serous otitis media. Presence of immune complexes and/or bacterial products capable of binding c1q results in formation of C1r-C1s-C1 IA complexes and may also cause the generation of C1r-C1s complexes. Such a dissociation of the C1 component will compromise the important opsonic function of the classical pathway.

C1 subcomponents in acute pneumococcal otitis media in children

Twenty children with acute pneumococcal otitis media were studied. In 6 children the infection ran a normal course and healed after the first episode and in 14 it relapsed. The serum levels of the immunoglobulins IgG, IgA and IgM were normal in all 20 children. Specific antibodies to pneumococcal polysaccharide were found in all cases, with no differences in the titers between the relapsed cases and those that healed. The complement components were quantitated with electroimmuno assay. G1q proved depressed in 60 per cent of the relapsed cases and in 16 per cent of the healed cases. C1r and C1s were disproportionally high compared with the C1q levels. Furthermore, crossed immunoelectrophoresis revealed abnormal complexes composed of C1r and C1s, and complexes composed of C1r, C1s and C1 IA. These complexes were more pronounced in sera from the children with relapsing otitis media.

Studies of C1 subcomponents in chronic urticaria and angioedema

C1q, C1r, C1s, C3, C4 and C-1 IA were determined by electroimmunoassay in sera from 150 patients with chronic urticaria or angioedema. Abnormal C1q and C1s levels were found in about 30% of the patients. In seven sera C1r was not measurable due to the appearance of diffuse precipitates. The levels of C3 and/or C4 were decreased in five sera with aberrations of C1 subcomponents in the electroimmunoassay. None of the patients showed reduced C-1 IA levels in the electroimmunoassay. The presence in sera of abnormal C1 subcomponent complexes was studied by crossed immunoelectrophoresis. Sera from 11% of the patients contained C1r-C1s complexes. Increased amounts of alpha2 complexes (C-1r-C-1-S-C-1 IA) were found in 33% of the patients. A major part of the C1q in sera yielding abnormal C1r precipitates had the same electrophoretic mobility as isolated C1q and was not associated with the C1qrs complex. C1 activity in hemolytic tests was low in these sera as well as in sera with decreased C1q levels. In the esterolytic assay for C-1 IA low values were found in 14 patients. Repeated sampling and family studies in appropriate cases gave no evidence for genetically determined deficiencies of C1q, C1r or C-1 IA.

C1 subcomponent conplexes in normal and pathological sera studied by crossed immunoelectrophoresis

Selected pathological sera gave three molecular species of C1s protein on crossed immunoelectrophoresis in the presence of calcium. C1s precipitates were obtained at the origin and in the beta1 and alpha2 regions. 12 normal sera gave C1s protein peaks at the origin and in alpha2 position. One of the normal sera also contained a small amount of the beta1 C1s protein. The C1s protein at the origin represented macromolecular C1. The alpha2 peak was a complex composed of C1 IA, C1s and C1r proteins. This complex was preformed in serum and did not show C4 cleaving activity. The molecular species in the beta1 region was shown to be a calcium-dependent complex of C1r and C1s, probably in proenzyme form. the C1r-C1s complex formed macromolecular C1 on addition of purified C1q to serum. During electrophoresis activation of C1 subcomponents was initiated by a mechanism involving CIr with generation of CIs activity in eluted fractions corresponding to the position of macromolecular C1 as well as in the beta region. The significance of beta1 C1s complexes or of alpha2 C1s complexes in normal and pathological sera was discussed.

C1R levels in normal human sera determined by electroimmunoassay

C1r levels in normal adults were determined by electroimmunoassay. The 95 per cent range was 71-133 per cent of a normal reference pool. C1r values were well correlated to the levels of C1q (r = 0.708) and of C1s (r = 0.768). The interplate variation of the method on double determinations was 3.4 (SD). C1r values in normal sera not appreciably affected by storage at room temperature or by repeated freezing and thawing. The C1r antigen in EDTA plasma was found to be labile.

Conversion of the fourth complement component studied by crossed immunoelectrophoresis

C4 in EDTA plasma and partially purified C4 give a β₂ peak on crossed immunoelectrophoresis. During electrophoresis C4 in serum is converted to a product of fast β₁ mobility, usually accompanied by a slow β₂ peak. Conversion in serum is inhibited by EDTA. Storage of serum at room temperature results in a gradual increase of the slow β₂ peak. Storage of EDTA plasma changes the configuration of the native β₂ peak. C[unk]s, trypsin, chymotrypsin, plasmin or thrombin added to partially purified C4 is capable of producing a fast β₁ C4 protein peak. C[unk]s, trypsin and chymotrypsin give this conversion product also when added to EDTA serum. C[unk]s, trypsin and chymotrypsin also give rise to a show β₂ and an inter α C4 conversion product in serum, probably consisting of complex formations between C4 and other serum proteins. Enzyme inhibitors known to interfere with C[unk] inhibit the conversion of C4 in serum on agarose electrophoresis. The results suggest that such conversion is caused by an activation of C1 during electrophoresis.

The concentrations of the fourth component of complement and of the C1 inactivator in synovial fluid from arthritic patients

The concentration of the fourth component (C4) of complement (C) in synovial fluid was immunochemically determined in forty-nine cases of arthritis. The lowest C4 values were found in the patients with rheumatoid arthritis (RA), in particular those with depressed synovial fluid C values (and positive rheumatoid factor tests), whereas the highest were obtained in cases of non-rheumatoid arthritis (pelvospondylites ossificans, Reiter's disease and psoriasis arthropathica) and in the majority of the sero-negative RA patients. Low C4 values also proved closely associated with low values for the third component (C3), and with pronounced conversion of this component. The C[unk] inactivator (immunochemically determined) of the synovial fluid which was correlated with the albumin concentration, did not vary with total C, C4 or C3.

A case of angioneurotic oedema with a high content of non-functioning, double peaked C1 esterase inhibitor

A high content of non-functioning C1 esterase inhibitor was found in serum and plasma from a patient with angioneurotic oedema. On antigen–antibody crossed electrophoresis the inhibitor appeared with a low peak normally located and a high more rapidly migrating peak in the α₁-fraction. No heredity for the disease was known.

Quantitation of the fourth complement component by electrophoresis in agarose gel containing antibodies

Electrophoresis in agarose gel containing antibodies can be used for quantitation of C4 in serum and plasma.

The normal range of the C4 concentration in serum and plasma varied between 40 and 200% of the standard pools. Low C4 values were found in systemic lupus erythematosus, in acquired haemolytic anaemia and in hereditary angioneurotic oedema.

Differences in C4 values were found between normal sera and the corresponding EDTA plasma, when tested after dilution in calcium-free and EDTA buffers, respectively. After storage of the samples for 1 day at 20°C or 37°C the C4 values decreased, most markedly in plasma; no further decrease was found on prolongation of storage, and the difference between serum and plasma C4 values disappeared. The plasma C4 levels gradually fell on storage at 4°C, but a clear difference between serum and plasma was still demonstrable after 5 days.

The method described is simple and quick and can be used routinely in large scale investigations.