immunodepletion

Immunodepletion refers to the deliberate reduction or removal of components of the immune system, either from a patient (in vivo) or from a biological sample (in vitro). It encompasses depletion of immune cells, immune proteins such as antibodies and complement, or broader immune mediators. In clinical practice, immunodepletion is used to treat autoimmune diseases, to minimize alloimmune reactions in transplantation, or as part of conditioning regimens for hematopoietic stem cell transplantation. Methods include plasmapheresis (plasma exchange), which removes circulating antibodies and immune complexes; immunoadsorption, which uses affinity columns to selectively bind and remove specific immunoglobulins or autoantibodies; and cellular depletion approaches that physically remove T cells or B cells from donor grafts or patient blood products.

In research and clinical laboratory settings, immunodepletion often refers to the removal of abundant immune-related proteins from body fluids to reveal less abundant components. Immunoaffinity-based depletion columns target proteins like albumin and the main immunoglobulins (IgG, IgA, IgM) to reduce dynamic range in proteomic analyses. This enhances detection of biomarkers but can co-deplete proteins that interact with targets and may introduce biases or sample loss.

Limitations and safety considerations include non-specific binding, incomplete depletion, and potential adverse events from blood-contact procedures. The choice of depletion strategy depends on the clinical goal, sample type, and balance between efficacy and potential loss of diagnostically relevant molecules.