immunology Question , please get me right answers 33) Many extracellular pathoge

Question

immunology Question , please get me right answers

33) Many extracellular pathogens cause disease by secreting which, in most cases. cannot be removed by the innate immunity but require specific antibodies to neutralize them. 34) Individuals with a disease called have abnormally thick mucus secretion or inhibition of ciliary movement, and thus frequently develop lung infections. 35) (5 pts) So far in our class, we have encountered two opsonins. What are they? In addition, briefly explain what they are doing as opsonins. 36) (5 pts) If your liver cells are infected with the Hepatitis B virus, they will present fragments (antigens) of the virus on their surface. However, these virus-infected cells are not considered (defined) as antigen-presenting cells. Explain why. 37) (5 pts) Although the MAC formation by complement activation originally was thought to be very efficient in killing pathogens. it turned out to be effective only against certain Gram?negative pathogens. Briefly describe the experiment that supported this conclusion.

Explanation / Answer

33. many extracellular pathogens cause disease by secreting ANTIGENS , which in most of the cases cannot be removed by the innate immunity but require specific antibodies to neutralize them

34. Individuals with a disease called cystic fibrosis , have abnormally thick mucus or inhibhition of ciliary movement

35. opsonins are the molecules which enhances the phagocytosis by marking an antigen , example include the antibodies igG , igM , complementary proteins C3B,C4B.

36. Many pathogens cannot recognise the antigens until they are represented by the major histo compatibility complex as the immune cells cannot go inside the cells .so they have to represented by the MHC molecules on the surface of the cells . in hepatitis they are taken by the dendrtitc cells , they cannot transport or represent these antigens to the immune system .

37. the MAC complex or terminal complement complex is a structure if formed on the surface of pathogeneic bacterial cells as a result of hosts alternative pathway,lectin pathway or classical pathway . these form the transmemberane channels . these form disruption of bilipid layer of target cells leading to cell lysis and death.

process; it consists of 4 complement proteins C5B,C6,C7,C8 . that bind to outer surface of plasma memberane and many copies of the fifth protein ,

formation of C5 -C7 complex ; complement protein C5 isconverted into C5a,C5b by the enzyme another complementary protein C6 binds to C5b complex C5BC6 complex will now bind to C7 ,his conformation allows the phospholipid to expose hydrophobic sites then polymerisation occurs C8-C9 occurs .it is inhibhited by the CD 59 this is present on the cells MAC.

in gram negative bacteria they can form the MAC complex but they cannot activate the complement activation . they break the lysosome of the bacteria . the MAC complex cannot act on gram positive bacteria

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