Immune complex-mediated toxicity

Immune complex deposition, immediate hypersensitivity, direct drug toxicity, and induction of anti-tissue antibodies have all been suggested. Interleukin-6 may be an important mediator of trimethoprim-induced aseptic meningitis in some patients. A case with three episodes after re-exposure to co-trimoxazole has been reported (41). Polymorphonuclear or mononuclear cells may preponderate (42). Interleukin-6 may be an important mediator of trimethoprim-induced aseptic meningitis in some patients (43,44). 

Toxicants affect the immune system in different ways. The effects are complex. Some substances suppress humoral immunity, others cell-mediated immunity, and certain toxicants stimulate specific immune functions. These effects may be classified... 

The cell surface contains antigens, which are referred to as CD, which stands for cluster of differentiation. The antibodies are produced against a specific antigen. When administered, usually by an intravenous injection, the antibody binds to the antigen, which may trigger the immune system to result in cell death through complement-mediated cellular toxicity, or the antigen-antibody cell complex may be internalized to the cancer cell, which results in cell death. Monoclonal antibodies also may carry radioactivity, sometimes referred to as hot antibodies, and may be referred to as radioimmunotherapy, so the radioactivity is delivered to the cancer cell. Antibodies that contain no radioactivity are referred to as cold antibodies. 

Whilst this may explain potentially explain many cases, this does not represent the full mechanism which is undoubtedly more complex as not all reactions appear to be immunological. For example, paracetamol is known to form reactive intermediates but yet is not involved in idiosyncratic reactions. Indeed, with some notable exceptions such as the penicillins, many drugs involved in idiosyncratic reactions do not mediate their toxicity through a immune response. 

Although assays for cell-mediated immunity are more complex and demanding, the possible need for them should always be considered because they may represent the source of a toxic action while accompanying antibodies are only a signal that an immune response has occurred. 

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