Autoimmunity and Transplantation Flashcards

Flashcards for key vocabulary and concepts related to autoimmunity and transplantation, based on lecture notes.

Central Tolerance

T cells undergo positive selection of pre-TCRs in thymic cortex and negative selection in BM and thymus. B cells undergo positive selection of pre-BCRs in BM and negative selection in BM and thymus

Peripheral Tolerance

Mechanisms that prevent activation of self-reactive lymphocytes

Antigen Segregation

Physical barrier to self-antigen access to lymphoid system

Peripheral anergy

Cellular inactivation by weak signaling without co-stimulus

Regulatory T cells

Suppression by cytokines, intercellular signals

Functional deviation

Differentiation of regulatory T cells that limit inflammatory cytokine secretion

Activation-induced cell death

Apoptosis of self-reactive lymphocytes

Immunological ignorance

Low-affinity interaction in absence of co-activation

Immunologically privileged sites

Sites like the brain, eye, testis, and uterus (fetus) that possess unique mechanisms to downregulate immune responses.

Rheumatoid arthritis

Auto reactive T cells, autoantibodies against antigens localized to joint synovium, and rheumatoid factor lead to joint inflammation and destruction causing arthritis

Graves' disease

Autoantibodies against the thyroid-stimulating hormone (TSH) receptor lead to Hyperthyroidism: overproduction of thyroid hormones

Hashimoto's thyroiditis

Autoantibodies and autoreactive T cells against thyroid antigens lead to destruction of thyroid tissue leading to hypothyroidism: underproduction of thyroid hormones

Systemic lupus erythematosus

Autoantibodies and autoreactive T cells against DNA, chromatin proteins, and ubiquitous ribonucleoprotein antigens lead to Glomerulonephritis, vasculitis, rash

Sjögren's syndrome

Autoantibodies and autoreactive T cells against ribonucleoprotein antigens lead to Lymphocyte infiltration of exocrine glands, leading to dry eyes and/or dry mouth; other organs may be involved, leading to systemic disease

Crohn’s disease

Autoreactive T cells against intestinal flora antigens lead to Intestinal inflammation and scarring

Multiple sclerosis

Autoreactive T cells against brain and spinal cord antigens lead to Formation of sclerotic plaques in brain and spinal cord with destruction of myelin sheaths surrounding nerve cell axons, leading to muscle weakness, ataxia, and other symptoms

Type 1 diabetes

Autoreactive T cells against pancreatic islet cell antigens lead to Destruction of pancreatic islet cells leading to nonproduction of insulin

Immunological ignorance

Lymphocytes that bind self antigens with relatively low affinity usually ignore them but in some circumstances become activated

Epitope spreading

Chronic autoimmune disease causes persistance of self-antigens, and more immune cells are activated by different epitopes, creating auto-Abs with different specificities

Organ-specific autoimmune diseases

Type 1 diabetes mellitus, Goodpasture’s syndrome, Multiple sclerosis, Crohn’s disease, Psoriasis, Graves’ disease, Hashimoto’s thyroiditis, Autoimmune hemolytic anemia, Autoimmune Addison’s disease, Vitiligo, Myasthenia gravis

Systemic autoimmune diseases

Rheumatoid arthritis, Scleroderma, Systemic lupus erythematosus, Primary Sjögren's syndrome, Polymyositis

Hyperacute graft rejection

Pre-formed antibodies against alloantigens on endothelium, causing blood clotting --> ischemic organ

Chronic allograft vasculopathy

Arteriosclerosis in vasculatures of grafted organs, particularly in heart and kidney, leading to hypoperfusion, fibrosis and atrophy

Graft-versus-host disease

Passenger leukocytes (T-cells) travel to host lymph tissues, get activated by host dendritic cells, proliferate and mount inflammatory response against host cells.

Molecular mimicry

Pathogenic antigens resemble host antigens, and host antibodies against pathogens cross react against host