Immunology | Immune system| Immunity

                Monoclonal antibodies are proving to be very useful as diagnostic,imaging,and therapeutic reagents in clinical medicine.Initially,monoclonal antibodies were primarily as in vitro diagnostic reagents.Among the many monoclonal antibody diagnostic reagents now available are products for detecting pregnancy,diagnosing numerous pathogenic microorganisms,measuring the blood levels of various drugs,matching histo compatibility antigens, and detecting antigens shed by certain tumors.
                Radiolabeled monoclonal antibodies can also be used in vivo for detecting or locating tumor antigens,permitting earlier diagnosis of some primary or metastatic tumors in patients.For example,monoclonal antibody to breast-cancer cells is labeled with iodine-131 and introduced into the blood to detect the spread of tumor to regional lymph nodes.This monoclonal imaging technique can reveal breast-cancer metastates that would be undetected by other,less sensitive scanning techniques.
Immunotoxins composed of tumor-specific monoclonal antibodies coupled to lethal toxins are potentially valuable therapuetic reagents.The toxins used in preparing immunotoxins include ricin,shigella toxin,and diphtheria toxin,all that s single molecule has been shown to kill a cell.Each of these toxins consists of two types of functionally distinct polypeptide comonents,an inhibitory(toxin)chain and one or more binding chains,which interact with receptors on cell surfaces;without the binding polypeptide(s) the toxin cannot get into cells and therefore is harmless.An immunotoxin is prepared by replacing the binding polypeptide(s) with a monoclonal antibody that is monoclonal antibody that is specific for a particular tumor cell.In theory,the attached monoclonal antibody will deliver the toxin chain sppecifically to tumor cells,where it will cause death by inhibiting protein synthesis.The initial clinical  responses to such immunotoxins in patients with leukemia,lymphoma,and some other types of cancer have shown promise,and research to develop and demonstrate their safety and effectiveness is underway.