Immune complexes in hemophilia

Frequency and clinical and transfusional significance of rheumatoid factor in patients with haemophilia and von Willebrand's disease

Using a solid-phase radioimmunoassay for IgM rheumatoid factor, increased levels were found in 24% or 82 patients with haemophilia A, in 4 of 11 patients with haemophilia B, in 2 of 11 patients with haemophilia A with inhibitors and in 4 of 12 with von Willebrand's disease. The levels of rheumatoid factor increased significantly (p less than 0.02) after factor VIII concentrate or cryoprecipitate transfusions. No clinical or transfusional side effects could be attributed in these patients in relation to the presence of rheumatoid factor.

Modulation of mononuclear phagocyte system function and circulating immune complexes by lyophilized concentrates in patients with classic hemophilia

Infusions of lyophilized antihemophilic factor concentrates in patients with hemophilia were found to affect both circulating immune complexes and in vivo mononuclear phagocyte system function. Following infusion nine patients had simultaneous assessment of serial immune complex levels and mononuclear phagocyte system clearance of IgG-sensitized autologous erythrocytes relative to a previously established baseline. Nine patients also had a separate second sequence, and two a third sequence, of serial immune complex measurements in relation to infusions. The net change in immune complexes over the 2- to 4-hr interval following infusion was consistent in 10 of 11 study pairs (P less than 0.01) despite different antihemophilic factor preparations for each study and different individual patient responses. This change could not be explained by immunochemical rearrangement in infusate and serum since in vitro mixing experiments showed no relationship to in vivo results. Change in mononuclear phagocyte system function showed a strong correlation with change in complexes (r = 0.70; P less than 0.05). It is suggested that infusions of antihemophilic factor can modulate the mononuclear phagocyte system which in turn alters immune complex levels. Both of these effects could potentially influence immune regulation which has been shown to be abnormal in other hemophiliac patient groups.

Circulating immune complexes in haemophilia and von Willebrand's disease

Sera from 63 patients with haemophilia A, 21 with haemophilia B and 29 with von Willebrand's disease were screened for the presence of circulating immune complexes (CICs), serological markers of hepatitis A and B virus, autoantibodies and factor VIII or factor IX inhibitors. CICs were detected by the 125J Clq binding assay (ClqBA), the solid phase conglutinin assay (KgBSP) and the solid phase Clq assay (ClqSP). The incidence of CICs detected by the ClqBA and the ClqSP methods in haemophiliacs and in von Willebrand patients was higher than that observed in normal subjects, while the prevalence of CICs detected by the KgBSP method was not. The presence of CICs was not correlated with patient age, severity of disease, presence of hepatitis B virus serological markers, abnormal liver function tests or factor VIII inhibitors. A significant connection was demonstrated between CICs detected by the ClqBA method and replacement therapy when the dose administered over 1 year was over 20 000 U of factor VIII or IX concentrates. The high proportion of CICs in von Willebrand's disease, not connected with the replacement therapy or the presence of serological markers of hepatitis virus, is in agreement with the possibility that immune complexes may be related to the disease itself and independent, at least in part, of exogenous agents.

Absence of circulating IgG immune Complexes in C57Bl/6 mice with age-associated renal IgG deposits

The L1210 enzyme-linked immunoassay (ELIA) for circulating immune complexes, previously developed for use in humans, has been adapted for use in mice. The assay detected elevated levels of immune complexes in 100% of NZB/W female mice (6-10 months old) with age-related immune complex-mediated glomerulonephritis. Application of the assay to the serum of one year old C57Bl/6 male mice failed to demonstrate elevated levels of serum immune complexes in spite of the routine finding of renal deposition of IgG plus proteinuria in aged mice of this strain. Since the L1210 ELIA detects all IgG-containing immune complexes, regardless of size or complement fixing capacity, these results suggest that the renal IgG deposits seen in aged C57Bl/6 mice are not derived from circulating IgG immune complexes.