How is pathogenicity of IC?

The pathogenicity of IC is partly dependent on the antigenantibody ratio. When the antibody is in excess, the complexes are insoluble, do not circulate, and are phagocytosed by macrophages in the lymph nodes, liver and spleen. However, when the antigen is in excess, the aggregates are smaller. They freely filter out of circulation in organs where the blood is transformed into fluids such as urine and synovial fluid. Therefore, IC affect glomeruli and joints Type III HS occurs when there is little antibody and an excess of antigen, leading to small IC being formed that do not fix complement and are not cleared from the circulation ➢ A soluble antigen is recognized by B lymphocytes but cannot be detected by T lymphocytes until it has been processed by an APC ➢ The receptors on the surface of B cells (BCRs) can bind to soluble antigens.