Hypersensitivity and Autoimmunity MCQs

Influenza is caused by virus - Myxovirus Influenzae. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 145.

Th2 cells mediate the activation and maintenance of the humoral or antibody-mediated, immune response against extracellular parasites, bacteria, allergens and toxins. Th2 cells mediate these functions by producing various cytokines such as IL-4, IL-5, IL-6, IL-9, IL-13 and IL-17E(IL-25). In immediate(type I) hypersensitivity, often called allergy, the injury is caused by TH2 cells, IgE antibodies and mast cells and other leukocytes. Mast cells release mediators that act on blood vessels and smooth muscle as well as cytokines that recruit and activate inflammatory cells. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 136.

Schwartzman reaction is a non-immunologic phenomenon in which endotoxin(lipopolysaccharide) induces local & systemic reactions; It can either be local or systemic type. Reference: Robbins, 9th ed, Pg: 208.

Hypersensitivity pneumonitis is an immunologically mediated inflammatory lung disease that primarily affects the alveoli and is therefore often called allergic alveolitis. Most often it is an occupational disease that results from heightened sensitivity to inhaled antigens such as those found in moldy hay. Reference: Robbins Basic Pathology, 10 th ed, Pg-514

Systemic sclerosis is an immunologic disorder characterized by excessive fibrosis in multiple tissues, obliterative vascular disease and evidence of autoimmunity, mainly the production of multiple autoantibodies. Although the term scleroderma is ingrained in clinical medicine, the name systemic sclerosis is preferred because excessive fibrosis is seen in multiple organs. Cutaneous involvement is the usual presenting manifestation and eventually appears in approximately 95% of cases. Systemic sclerosis is a chronic autoimmune disease of still not fully understood pathogenesis. Fibrosis, vascular wall damage and disturbances of innate and acquired immune responses with autoantibody production are prominent features. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 159.

Sjogren syndrome is a chronic disease characterized by dry eyes(keratoconjunctivitis sicca) and dry mouth(xerostomia) resulting from immunologically mediated destruction of the lacrimal and salivary glands. It occurs as an isolated disorder(primary form), also known as the sicca syndrome or more often in association with another autoimmune disease(secondary form). Lacrimal and salivary glands are the major targets of the disease, but other exocrine glands, including those lining the respiratory and gastrointestinal tracts and the vagina, also may be involved. The earliest histologic finding in both the major and the minor salivary glands is periductal and perivascular lymphocytic infiltration. Later there is atrophy of the acini, fibrosis and hyalinization; still later in the course, the atrophic parenchyma may be replaced with fat. Reference: Robbins Basic Pathology, 10 th ed, Pg: 158.