Question

4. We said that many disease agents work by causing an excessive inflammatory response. Explain how each of the following leads to more than the desired amount of inflammation.

a. Superantigen toxin

b. Lipopolysaccharide

c. The hypersensitivity response associated with Lupus

Answer 1

a. Superantigen toxin:

• It works by increasing T cell amount - ( no specifications- like whether it is a helper T cell or killer etc...) and also increasing the cytokines release..
• This toxin is produced by viruses and bacterias as their defense mechanism.
• it reduces the effectiveness of adaptive immunity by generating enormous immune response by the T cells, which is not at all specific to any epitopes presented on this antigen.
• cytokines in turn activates interferon-gamma and thus activates many macrophages and other antigen presenting cells, which in turn again increased the release of interferons and TNF-alpha- leading to shock, thus escaping the immune system of host.

b. Lipopolysaccharide

• It cause the activation of toll like receptor 4, which cause the release of NADPH oxidase and NF kappa B,
• It also induces release of proinflammatory cytokines, and it has an ability to activate, IL-8 and other inflammatory cytokines
• These all stimulate iflammatory response in host

c. The hypersensitivity response associated with Lupus

• Type III hypersensitivity is associated with Lupus
• This hypersensitivity occurs due to circulating antigen- antibody complexes , which cause activtion of classical pathway complement cascade, which cause destruction of self tissues , when the immune system try to phagocyte immune complex.
• This cause release of proteolytic enzyme and other proinflammatory cytokine,