An immunotoxin is a chemical that can cause immune system malfunction with exposure. When the immune system function is suppressed (immunosuppression) there is an increased susceptibility to infectious diseases and cancers. Polychlorinated-biphenyls (PCB), asbestos and herbicide DDT are known immunosuppressants. Immunotoxins can also cause autoimmune disease, where an overactive immune system attacks the bodies cells.
Therapeutic immunotoxins are compounds that are being developed for cancer and virus treatment. These immunotoxins are chimeric protein that are linked to a toxin. The protein is a modified antibody that targets a specific cell type. When the protein binds to that cell, it is taken in and the toxin kills the cell.