Increased antibody levels can lead to immune complex deposition, particularly in blood vessel walls, potentially causing organ damage. This process, occurring in the presence of excess antigen, can manifest within hours if antibody levels rise rapidly, or over several days in conditions like serum sickness.
In more detail:
- Immune Complex Formation: Antibodies bind to antigens (foreign substances), forming immune complexes. These complexes circulate in the bloodstream.
- Deposition in Tissues: If there are too many immune complexes, or if they are of a certain size, they can deposit in various tissues, especially blood vessel walls, the kidneys (glomeruli), and joints.
- Inflammation and Damage: Once deposited, these immune complexes activate the complement system and attract inflammatory cells (like neutrophils). This leads to inflammation and tissue damage.
- Organ Damage: The specific organs affected and the severity of damage depend on where the immune complexes deposit. For example, deposition in the kidneys can cause glomerulonephritis (kidney inflammation), while deposition in blood vessel walls can cause vasculitis (blood vessel inflammation).
Timeframe and Conditions:
- Rapid Antibody Increase: When antibody levels increase rapidly in the presence of persistent antigen, immune complex deposition can occur within hours, leading to acute inflammatory reactions.
- Serum Sickness: This is a classic example where immune complexes form over several days as antibody levels rise against a foreign protein (antigen), leading to fever, rash, joint pain, and potentially kidney problems. The severity is proportional to the rising antibody levels and the persistence of the antigen.
In summary, while antibodies are crucial for immune defense, elevated levels, especially with circulating antigens, can paradoxically lead to tissue damage and inflammation through immune complex deposition.
