Final answer:
Autoimmune diseases often implicate B cells and autoantibodies, but diseases like Type 1 diabetes mellitus, multiple sclerosis, psoriasis, and Crohn's disease involve rogue T-cells. These result from failures in immune regulation, genetic disposition, and potential environmental factors.
Step-by-step explanation:
Autoimmune diseases commonly involve the adaptive immune system, and while many are associated with autoantibodies produced by B cells, there are indeed disorders primarily caused by rogue T-cells. Examples of such diseases include Type 1 diabetes mellitus, where autoreactive T cells attack insulin-producing beta cells in the pancreas, and multiple sclerosis (MS), where myelin-reactive T cells contribute to the destruction of the myelin sheath of nerve fibers. Other disorders like psoriasis and certain types of inflammatory bowel disease (IBD), such as Crohn's disease, also involve pathogenic T cell responses. The precise cause of these malfunctions in the immune system is not completely understood, but involves a combination of genetic factors, environmental triggers, and anomalies in immune regulation, where regulatory T cells fail to restrain autoreactive T cells that escaped thymic deletion.