Question

1. Alterations in Immune Function
   1. How do type 1, 2, 3, and 4 hypersensitivity reactions differ according to mechanism of action?
   2. What are the clinical features of the common immunodeficiency disorder?

Answer 1

ANSWER- Hypersensitivity reaction 1-  Another name Anaphylactic reaction .In this fast response which occurs in minutes , rather than multiple hours or days . Free antigens cross link the IgE on mast cells and basophils which causes a release of vasoactive biomolecules . Testing can be done via skin test for specific IgE.

Hypersensitivity reaction 2 - Another name cytotoxic reaction .In this antibody (IgM or IgG) binds to antigen on a target cell , which is actually a host cell that is perceived by the immune system as foreign , leading to cellular destruction via the MAC . Testing includes both the direct and indirect coombs test.

Hypersensitivity reaction 3 -Another name Immune complex reaction. In this antibody (IgG) binds to soluble antigen , forming a circulating immune complex . This is often deposited in the vessel walls of the joints and kidney, initiating a local inflammatory reaction.

Hypersensitivity reaction 4- Another name cell mediated immune memory response reaction . In this T helper cells are activated by an antigen presenting cell. When the antigen is presented again in the future , the memory T helper cells will activate macrophages and cause an inflammatory response . This can lead to tissue damage.

Clinical features of common immunodeficiency disorder -

• Bronchitis
• sinus infection
• meningitis
• thrombocytopenia
• anemia
• cramps in abdomen
• loss of appetite
• delayed growth and development
• automimmune disorder such as lupus erythmatous , rheumatoid arthritis