BIOL 221 Lecture Notes - Lecture 6: T Helper Cell, Mhc Class Ii, Co-Stimulation

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MHC Classes: Class II

•cells involved in immune response (APCs including macrophages,

dendritic cells and B cell lymphocytes)

•display “foreign” proteins

● MHC class II proteins are displayed by cells involved in the immune

response including APCs and lymphocytes.

● In this case the display of MHC and antigen is linked to activation of

specific T cells or B cells.

Activation & Costimulation

•Activation requires both:

•Interaction of MHC class II/antigen complex with antigen receptor on T or

B cell, AND

•Either:

–interaction with surface molecule on APC, or target cell; OR

–cytokines secreted by leukocytes

● Activation of a T cells requires both interaction of the MHC class

II/antigen complex with antigen receptor on T or B cell and

costimulation.

● Costimulation occurs either through interaction with a specific surface

molecule on the APC or target cell, or through cytokines.

Costimulation (con’t)

•Helper T cells activated first

•B cell engulfs and processes antigens and displays on MHC II

● Helper T cells are normally activated first when an antigen displayed

on MHC class II protein of an APC interacts with receptors on the T

cell.

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Document Summary

Mhc classes: class ii: cells involved in immune response (apcs including macrophages, dendritic cells and b cell lymphocytes, display foreign proteins. Mhc class ii proteins are displayed by cells involved in the immune response including apcs and lymphocytes. In this case the display of mhc and antigen is linked to activation of specific t cells or b cells. Activation & costimulation: activation requires both, interaction of mhc class ii/antigen complex with antigen receptor on t or. Interaction with surface molecule on apc, or target cell; or. Activation of a t cells requires both interaction of the mhc class. Ii/antigen complex with antigen receptor on t or b cell and costimulation. Costimulation occurs either through interaction with a specific surface molecule on the apc or target cell, or through cytokines. Costimulation (con"t: helper t cells activated first, b cell engulfs and processes antigens and displays on mhc ii.

Related Questions

Like T cells, B cells require multiple signals for activation. Antigen binding to the B cell antigen ______ provides one signal, while antigen-specific effector ______ provide the other signals. The requirement for multiple signals to activate either a T cell or a B cell helps to prevent ______ and dangerous activation of monocytes , including ______ ______ . Most of the proteins involved in cellâcell recognition and antigen recognition in the immune system, including ______, TCRs, and ______ proteins, as well as various co-receptors, belong to the ancient Ig superfamily. This superfamily is thought to have evolved from a primordial gene encoding a single Ig- like ______ . The mechanisms for diversifying antibodies and T cell receptors by recombining gene segments may have arisen when a ______ inserted into an exon of a gene encoding an Ig family member.

receptors (BCRs) helper T cells killer T cells
inappropriate appropriate monocytes
lymphocytes self-reactive non-self-reactive
antibodies IPR MHC
domain transposon retrovirus

tanmacaw520

Fill in the blanks in the following paragraph using words from the word bank below. Not all words will be used, and some may be used more than once.

Like T cells, B cells require multiple signals for activation. Antigen binding to the B cell antigen __________provides one signal, while antigen-specific effector ________ provide the other signals. The requirement for multiple signals to activate either a T cell or a B cell helps to prevent _______ and dangerous activation of _________ , including __________ _________. Most of the proteins involved in cellâcell recognition and antigen recognition in the immune system, including _________ , TCRs, and _______ proteins, as well as various co-receptors, belong to the ancient Ig superfamily. This superfamily is thought to have evolved from a primordial gene encoding a single Ig- like _______ . The mechanisms for diversifying antibodies and T cell receptors by recombining gene segments may have arisen when a _________ inserted into an exon of a gene encoding an Ig family member.

receptors (BCRs) helper T cells killer T cells
inappropriate appropriate monocytes
lymphocytes self-reactive non-self-reactive
antibodies IPR MHC
domain transposon retrovirus

plumsquirrel992

Immunology worksheet help?

In people infected with human cytomegalovirus, class I MHC andb2-microglobulin are produced, but very little mature class I MHCis found at the cell surface. Inhibition of which of the followingmolecules by human cytomegalovirus may account for thisphenomenon?

A.	TAP
B.	Ii
C.	TCR
D.	CLIP
E.	RAG

Your chances of having the same MHC haplotype as your siblingare:

A.	1:2.
B.	1:4.
C.	1:16.
D.	1:8.
E.	1:1.

Which of the following is the BEST example of self-MHCrestriction of T cells?

A.	A T-cell clone is deleted when it binds too tightly to selfMHC.
B.	A T-cell clone responds more vigorously to a self-peptide thana foreign peptide.
C.	A T-cell clone recognizes foreign MHC.
D.	A T-cell clone only recognizes foreign peptides when presentedby self MHC.
E.	All of the above

MHC molecules:

A.	are conserved between individuals.
B.	bind repeating patterns found on pathogens.
C.	are recognized by T cells.
D.	are membrane-bound molecules found exclusively on T cells.
E.	are secreted by T cells and bind and neutralize antigen in theserum.

Tasmanian devils are a largely inbred population with littlediversity in the MHC. Which of the following would be a likelyoutcome of this?

A.	They would compensate for low diversity in the MHC with highdiversity in the TCR.
B.	They would compensate for low diversity in the MHC with highdiversity in the BCR.
C.	They would rely only on innate immune responses.
D.	They would be at higher risk of infection.
E.	All of the above

How many different MHC classical class I proteins does eachnucleated cell in a human heterozygous at the MHC locusexpress?

A.	Six
B.	Two
C.	Three
D.	One
E.	None. Only APC express class I.

MHC polymorphisms tend to cluster:

A.	in the peptide-binding groove.
B.	in the transmembrane domain.
C.	in the coreceptor contact residues.
D.	in the framework region.
E.	All of the above

A mutation that renders the MHC class II molecule DMnonfunctional would likely lead to:

A.	cells with no class II MHC.
B.	a deficiency in CD8⁺ T cells.
C.	cells with class II MHC only bound with CLIP.
D.	cells with class II MHC bound with a variety ofself-antigens.
E.	cells with no DO.

The human MHC locus is one of the most polymorphic regions ofthe genome. What does this mean?

A.	This region is regulated by many different mechanisms.
B.	Sequence variability is low in this region.
C.	There are many introns in this region.
D.	There are many different alleles of these genes.
E.	It has the most different genes.

10.

Which of the following is an example ofcross-presentation?

A.	An exogenous peptide being presented on MHC class II
B.	A B-cell antigen being presented to a T cell
C.	An endogenous peptide being presented on MHC class I
D.	An endogenous peptide being presented on MHC class II
E.	An exogenous peptide being presented on MHC class I

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BIOL 221 Lecture Notes - Lecture 6: T Helper Cell, Mhc Class Ii, Co-Stimulation

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