Question

11. Ovalbumin (Ova) is the predominant protein in egg white (of chickens and other birds), and has long been a model antigen in immunological studies (initially because of its easy availability, and then later, because sometimes it is easier to study new things about an existing protein than to start from scratch using an uncharacterized reagent). Originally, it was used to study antibody generation (eg by injecting it into mice). However, it has also been used to study MHC-based antigen presentation to T cells SIINFEKL is a peptide (single letter amino acid code) from Ova that can be presented in this way, and different T-cell clones that recognize SIINFEKL presented on various MHC proteins have been generated. One such T cell clone is used in the experiments presented here, which show the secretion of the Interleukin-2 (IL-2) cytokine by these T cells after mixing with B cells that have been treated in various ways. Electroporation is a technique that temporarily disrupts the cellular membrane and allows molecules to be introduced into cells (cytoplasm). Analyse the data below, and answer the questions that follow 20 20 10 10 10 10 # B cells added # B cells added (a) B cells were electroporated either with ovalb umin (solidline) or with a control protein (dashed line) notrecognized by the clonal T cell population 20 (b) B cells were firstincubated with an inhibitor of lysosomal catbepsin proteases (cystatin, solid line) or an inhibitor of the proteasome (MG132, dashed line), and then electroporatedwith ovalbumin. 10 (c) B cells were electroporated with the SIINFEKL peptide,and then incubated in the presence (dashed curve) or absence (solid curve) of the MG132 proteasome inhibitor (disregard the dotted line) # B cells added lla. What information is derived from the use of lysosomal protease vs proteasome inhibitors (panel b)? 1lb. What kind of T cells are being added to the assay? How can you tel1? (at least 3 different clues!) llc. Whx do you think the presence or absence of the proteasome inhibitor made a big difference in (b) but no difference in (c)?

Answer 1

11a. the cystatins  inhibitor of lysomal cysteine protease and activate the apoptosis. on the otHer hand MG-132 inhibit the tumor cell growth by inducing cell arrest and triggering apoptosis.

11b. CD8+ tcell

clue: 1. SIINFEKL for stimulation of ovalbumin specific CD8+ T cell.

2. CD8+ T cell have the ability to make some cytokine.

3. MHC molecule bind to T cell receptor and CD4+/CD8+ coreceptor

11c. the presence of proteasome inhibitor induce the apoptosis that makes a big difference .