title: [Transplantation immunology: mechanism of rejection. Mode of action of immunosuppressive drugs].
abstract: Allograft rejection is an immunologic process comprising two distinct phases. During the first phase, the various protagonists that will contribute to the destruction of the target organ assume their roles: presentation and recognition of the antigen by the helper T cells responding to class II antigens, proliferation and differentiation of helper T lymphocytes with production of various lymphokines (in particular IL2), action of these lymphokines on precursor effector cells and lastly generation of destructor mechanisms. Phase II is the attack and destruction of the allograft by these protagonists. Clinically this phase is termed rejection. It is composed of three periods: recognition, attack and destruction of the target. Destruction of the graft always occurs in the same manner, but its clinical and pathological expression varies according to the intensity of the phenomenon and according to which effector agent (cells or antibodies) is predominant. The process is permanent and evolves in wave-like fashion. Its variations are more frequent, shorter and more intense during the first months posttransplantation. The intensity and frequency of these variations decreases with time. Thus, rejection episodes may be hyperacute, acute or chronic. All the structures of the grafted organ may be the site of lesions, but the vessels are the main target. Knowledge of these various phases in rejection makes it possible to make maximal use of presently available immunosuppressive agents according to their modes of action.
mesh_terms: D000276:Adjuvants, Immunologic / Q000627:therapeutic use; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D000917:Antibody Formation; D000961:Antilymphocyte Serum / Q000627:therapeutic use; D006084:Graft Rejection; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008222:Lymphokines / Q000276:immunology; D010974:Platelet Aggregation / Q000187:drug effects; D013601:T-Lymphocytes / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014181:Transplantation Immunology
chemical_list: D000276:Adjuvants, Immunologic; D000305:Adrenal Cortex Hormones; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000911:Antibodies, Monoclonal; D000961:Antilymphocyte Serum; D007166:Immunosuppressive Agents; D008222:Lymphokines
vernacular_title: Immunologie de transplantation: mécanismes du rejet. Mode d'action des drogues immunosuppressives.