Question

7. True or False: When the immune response is not properly regulated and becomes activated inappropriately, conditions like asthma and autoimmunity occur. a. True b. False 8. Which of the following is true about antimicrobial peptides? a. Produced in an inactive form b. Form pores in the microbial membrane to induce lysis c. Are expressed in specific tissues of the body d. All of the above e. None of the above 9. Which of the following is NOT a function of complement? a. Opsonization of pathogens to induce phagocytosis b. Directly lysis a pathogen by forming the membrane-attack complex C. Induce inflammation d. Activate adaptive immunity 10. The three complement pathways converge at the: a. Cleavage of C3 into C3a and C3b b. Activation of C5 C. Complex formation between C5b, C6, C7, C8 and 29 d. Inhibition of C3bBb

Answer 1

Ans. 7) True.

When immune response in uncontrolled manner against the self antigen are known as autoimmunity and and when response against foreign antigen are dysregulated or uncontrolled results in tissue injury are known as hypersensitivity disease. Asthma is an example of type 1 hypersensitivity, in this helper T cells stimulate the production of IgE antibody against the allergen. During this response, sometimes hyper-responsiveness caused by smooth muscle contraction also inflammation and tissue injury is caused by cytokines and other late phase reaction, this hyper reaction cause asthma.

Ans. 8) All the above are true.

Antimicrobial peptides and proteins (AMPs) are a diverse class of naturally occurring molecules that are produced as a first line of defense by all multicellular organism. AMPs are produced in inactive form and when they enter the microbial cell it get activated. AMPs typically consist of between 10-50 amino acid residues with an overall positive charge allowing them to selectively bind to negatively charged bacterial membranes. Selectivity for specific species is due to differences in the membrane composition of different microbes and cell types. Defensins and cathelicidins are membrane-disrupting peptides in vertebrates. The defensins play important roles against invading microbes. They act against bacteria, fungi and viruses by binding to their membranes and increasing membrane permeability, cathelicidin action involves the puncturing of cell membranes of organisms, it rapidly destroys the lipoprotein membranes of microbes enveloped in phagosomes after fusion with lysosomes in macrophages.

Ans. 9) activation of adaptive immunity is not the function of complement system.

Complement system have three functions:

• Opsonization and phagosytosis: C3b protein bind to the microbe and this C3b bound microbe is recognized by the type 1 complement receptor (CR1 r CD35) results in phagosytosis of microbe.
• Complement mediated cytolysis: binding of C3b to microbe activates the late component of complement, i.e, C5, C6, C7, C8, C9. These are responsible for MAC (membrane attack complex) formation, results in osmotic lysis of microbe.
• Stimulation of inflamatory reactions: proteolytic cleavage of C3, C4 and C5 to release C3a, C4a, C5a activates the leukocytes, i.e., neutrophils, results in release of inflamatory mediators that help in elimination of microbe.

Ans. 10) last step of complement pathway is formation of C5b, Cy, C7, C8 and C9. C5b initiate the assembly of MAC, C6 bind to Ctb and recruit C7, C7 bind to C5b and C6 and i sert i to lipid membrane. C8 bind to the formed complex and initiate polymerisation of C9 and C9 polymerise to form pores through which water and ions can enter, causing death of the cell. This poly C9 is called MAC.