Question

10-13 Explain briefly how immunological memory oper ates in (A) the short term and (B) the long term 10-14 Natural killer cells (NK cells) carry activating and inhibitory receptors on their surface. A. What property of NK cells do these receptors acti- vate or inhibit, respectively? Explain your answer. B. How are NK cells thought to use these receptors to recognize and eliminate virus-infected cells? C. Why are the actions of NK cells categorized as innate immunity, and what do we know of their specificity for MHC class I molecules? D. Why do the NK cells of the recipient of an organ transplant sometimes attack the transplanted tissue? 10-15 A. Describe the ligand for the NK-cell receptor CD94:NKG2A. B. Why is the concentration of this ligand on the tar- get cell an effective measure of the presence or absence of classical MHC class I molecules?

Answer 1

10-13

a-Short term memory; this is the memory which is retained by plasma cells type of B cells, which remains in blood for some time. If during this time, infection occur by same pathogen, then this plasma cell activate and helps in killing of pathogen in blood.

b- long term memory: This type of memory is retained by memory cells types of B cells which are generally occur for long period of time. These cells remains in resting stage during its life time and when pathogen attack in future, they kill the pathogen.

10- 14

A-NK cells has receptor which interact with MHC 1 class receptor present on cells. If these MHC 1 recpetors are present in a cell during interaction withNK cells, NK cells are in inactive state.

but viruses do not have such MHC! receptor on their surface. When NK cells inreact, then they do not found corresponding MHC1 recptor and come in active state.

B- As decribedabove, when there is no interaction , then perforin protein make transporter channel which secrete grana enzyme in the cells of virus, this grana further activate the procaspase in virus and leads to apoptosis in virus cell and ultimately leads to death of the virus cell.

C- NK cells are categorise as element of innate immunity beacuse these recptors presen ton NK cells are from birth of an individual in NK cells. FOR their activation, NK cells interaction should ot occur with MHC1 recptor of target cell.