Immunoadsorption as a tool for the immunomodulation of the humoral and cellular immune system in autoimmune disease.

Immunoadsorption onto staphylococcal protein A is a newly developed semiselective extracorporeal adsorption technique for immunoglobulins applied in patients suffering from severe autoimmune disease. Its effect on the humoral and cellular immune system was investigated using standard immunological assays. The elimination capacity for total IgG and IgG subclasses 1, 2, and 4 was more than 90% but for subclass IgG3 varied between 30 and 90%. Autoantibodies, e.g., anti-dsDNA, anti-glomerular basement membrane (anti-GBM), anti-cardiolipin, and anti-human leukocyte antigen (anti-HLA) antibodies, were eliminated in comparable amounts. The affinity of protein A for circulating immune complexes (CIC) was 300 times greater than for soluble IgG. HLA-II expression on monocytes and T lymphocytes was reduced over time during repeated IAs (IA). The number of activated T lymphocytes declined while the percentage of naive T cells increased. A diminished CD4/CD8 ratio normalized during IA treatment. These results indicate that IA actively modulates the humoral as well as the cellular immune system in addition to its immunoglobulin reducing effect.