Effects of antigen-antibody complexes on the primary immune response in Rhesus monkeys

Opsonization of alphaviruses in hamsters

Immune elimination of alphaviruses in immunized hamsters appears to involve formation of virus/antibody aggregates which are subsequently cleared from the circulation by cells of the reticuloendothelial system (RES). Virulent strains of Venezuelan (VEE) and Western equine encephalitis (WEE) viruses which were cleared slowly from the circulation of nonimmune hamsters, were cleared rapidly when inoculated into the blood of immunized hamsters. Likewise, when these viruses were mixed with specific hamster immune serum prior to inoculation, they were efficiently cleared from the circulation of nonimmune hamsters. Virus, mixed with specific immune serum, or inoculated into immunized hamsters, formed virus/antibody aggregates, as demonstrated by density gradient centrifugation, filtration through polycarbonate membranes, precipitation with Staphylococcus protein A, and electron microscopy. Cleared virus was concentrated primarily in liver and spleen, as confirmed by autoradiography. Immune clearance of virulent VEE was demonstrable within 5 to 6 days following immunization of hamsters with live attenuated VEE vaccine, strain TC-83. In these hamsters, a close association was established between formation of virus/antibody aggregates, rapid clearance, and survival of challenged hamsters. Adsorption of virus to hamster macrophages in culture was enhanced by immune serum in the presence of complement. These results are compatible with the hypothesis that immune clearance of virus in the intact hamster involves a complement-dependent interaction of virus/antibody complexes with cells which possess Fc and complement receptors. The clearance of immune complexes by the RES serves to amplify the protective effect of neutralizing antibody alone.

Pathopysiological aspects of immune complex diseases. Part II. Phagocytosis, exocytosis, and pathogenic depositions

Elimination of IC by the phagocytic system occurs mainly by macrophages and contrarotates to the pathogenic effect. Decisive to prevent systemic IC disease is the capacity of the phagocytic system. In the case of its saturation, the danger of the occurrence of IC disease is greatly enhanced. Conclusive evidence seems to exist that IC of extremely small or extremely high lattice structure (precipitates) are less pathogenic than soluble IC of medium network. Small IC in extreme antigen and antibody excess or precipitates exhibit a reduced complement activating potency. Small IC in extreme antigen or antibody excess hardly interact in vitro with membrane receptors and do not induce IC disease when injected or formed in vivo. Highly lattices IC, especially precipitates, are eliminated extremely quickly from the circulation, mainly by macrophages and there deposition in the kidney is significantly reduced. Thus, lack of quality of the antibody to precipitate the antigen and a reduced capacity and effectivity of the phagocytic system to eliminate the IC may be extremely important in the generation of IC diseases. Facing the overwhelming and partly even inconsistant data of this topic, one may doubt whether IC diseases may be regarded to be a defined and coherent disease. Too many variables and questions exist concerning the nature of the antigen, especially in tumor and autoimmune diseases, concerning the quality of the antibody and the characteristics of the pathogenic IC and concerning localization and the elimination process. Nevertheless, common pathophysiological pathways of IC diseases may be recognized.

Autoimmune implications of immune complexes in clinical variants of hepatitis B

Immune complexes (IC) were investigated in sera from 208 individuals with various clinical types of viral hepatitis diagnosed by clinical and laboratory criteria, including liver biopsy. Immune complexes were assessed by platelet aggregation (PI A) and by radioimmunoassay (RIA). The data were related to autoimmune phenomena (especially rheumatoid factors) and to the role that the IgM class of hepatitis B (HB) antibody might have in IC formation. Although the highest frequency of P1 A was in the few sera from patients with cirrhosis or hepatoma, the next highest was in sera from acute hepatitis patients (71%), and the lowest in sera from chronic active (57%) and chronic persistent (46%) hepatitis patients. A proportional number of patients with IC's were positive for hepatitis B surface antigen (HBs). A parallel prevalence was noted between P1 A and autoantibodies, with anti-Ig's being found more frequently in sera from acute hepatitis and chronic active hepatitis patients. The relationship between RIA results for complexes and RIA results for anti-IgG was inverse, as though anti-IgG interfered with IC reactivity by RIA. Anti-IgM pre-incubated with sera increased the amount of P1 A in sera from patients with acute hepatitis as well as in those from patients with chronic persistent hepatitis, suggesting a more frequent IgM involvement in IC's in these diseases than in chronic active hepatitis. Whereas liver cell damage in acute and active hepatitis may reflect elevated autoantibodies, the IgM class of HBs antibody may be involved in acute as well as chronic persistent hepatitis.

Platelet aggregation by hepatitis B surface antigen-antibody complexes

Platelet aggregation indicating antigen-antibody complex formation was observed when hepatitis B surface (HBs) antigen and antibody were mixed. Platelet aggregation titers were determined for serum specimens found positive by radioimmunoassay for either HBs antigen or HBs antibody. From these determinations, incidence of HBs antigen-antibody complexes was found to be higher in HBs antigen seraas than in HBs antibody sera. There was an inverse correlation between platelet aggregation titers and radioimmunoassay values that was statistically significant for HBs antigen sera but not for HBs antibody sera. The incidence of anti-complementary activity was twice as high for platelet aggregation-positive HBs antigen and antibody sera as for platelet aggregation-negative sera. HBs antigen sera that were positive by platelet aggregation exhibited nearly three times the incidence of anti-complementary activity as did HBs antibody sera. However, the low incidence of anti-complementary activity was distributed about equally between HBs antigen and antibody sera that were negative by platelet aggregation. Additional HBs antigen preincubated with HBs antigen-positive sera effectively inhibited platelet aggregation, whereas additional HBs antibody was somewhat less effective. On the other hand, preincubation of HBs antigen sera with anti-IgG serum effectively enhanced platelet aggregation, whereas preincubation of HBs antigen sera with HBs antibody did not.

Modified polyriboinosinic-polyribocytidylic acid, an immunological adjuvant

Stabilization of polyriboinosinic-polyribocytidylic acid against enzymatic hydrolysis by addition of poly-1-lysine and carboxymethylcellulose (PICLC) resulted in a compound with marked adjuvanticity. The primary antibody response of rhesus monkeys to formalin-inactivated Venezuelan equine encephalomyelitis virus vaccine was significantly potentiated if the vaccine was combined with PICLC prior to vaccination. The antibody response was maintained at a significantly higher level than controls for 2.5 months postvaccination and paralleled immunological responses reported for live, attenuated (TC-83) vaccine.

Adjuvant effects of diethylaminoethyl-dextran

Diethylaminoethyl-dextran exhibited a significant effect on the primary immune response of rhesus monkeys to formalin-inactivated Venezuelan equine encephalomyelitis virus vaccine (IVEE). Antibody formed to IVEE and adjuvant followed a classic immunoglobulin M-immunoglobulin G pattern; however, as compared with vaccine alone, use of this adjuvant with IVEE reduced the time required for onset of immunoglobulin G synthesis.