M&I Exam 2: Major Histocompatibility Complex

endogenous antigens

-antigens are those that are synthesized by the same cell that is producing the MHC class I molecule -antigens are generally viral antigens although neo- or tumor antigens would also be in this class

a1 and a2 (Class I)

-the _____ and _____ domains form a binding groove for binding antigen -the major structural variability occurs

-MHC Class II molecules -alpha and beta chain -a1, a2, B1, B2

-these are products of the HLA-D region genes -the molecule is composed of 2 chains -each chain has 2 external domains

chromosome 15 (Class I)

B2 microglobulin is not produced by MHC genes. Comes from chromosome ____

-determinant selection -immunodominant epitopes

It is this property of selective binding and presentation of peptides (_________________________) that determines which peptides will be presented and, therefore, which epitopes will induce an immune response (____________________________________)

12

MHC Class II molecules are comprised of 2 chains (a and B) and there are 3 major genes for each (DR, DP, DQ). When you do the mixing and matching with genes from Mom and Dad, each APC can express at least ____ different class II molecules

T helper cells

MHC Class II presents antigen to CD4+ __________________ cells.

RER

MHC class II are synthesized in the ________ and transported through the Golgi apparatus in a transport vesicle where they fuse with a phagolysosome containing processed antigen

CD4+

T helper cells

True

True/False: MHC molecules bind both foreign and self peptides

transmembrane domain and a cytoplasmic tail

both the alpha chain and B chain have a ____________________ and an ___________________________

MHC Class III

contains genes that code for complement components and tumor necrosis factor (TNF)

CD8+

cytotoxic T cells

MHC Class II

genes in the HLA-D region code for the production of this molecule. The main genes are DR, DQ, and DP

CTLs

immunologically, MHC class I primary function is to present antigen to CD8+ T cells (______)

antigen-binding groove

in MHC class II molecules the __________________________ is between a1 and B1

HLA (human leukocyte antigen)

in humans, the MHC is termed _______

H-2

in mice, the MHC is termed ______

MHC Class I and II

in terms of immune responsiveness, there are 2 major types of MHC molecules

TCR

in the case of the immune system, this cell is a T cell and the ______________ recognizes the combination of processed Ag and MHC

B2 microglobulin (Class I)

is a small globular peptide non-covalently linked to the a3 domain of the alpha chain

Class II molecules

molecules bind 10-30 amino acid length peptides

Class I molecules

molecules bind peptides that are 8-11 amino acids long

MHC class II molecules

molecules present antigen that is of exogenous origin (outside the cell). Antigen-presenting cells endocytose and process exogenous Ag

antigen

once the antigen-loaded MHC molecule (class I or II) is expressed on the cell surface, it can present _____________ to any cell with the appropriate receptor

NK recognition

other class I genese (HLA-E, -F, -G and -H) code for minor class I molecules, a few of which have been defined with specific function (_____________________)

MHC class I

presents endogenous antigens

proteosomes (class I)

proteinase complexes in the cytoplasm, process endogenous antigens into peptides 8-11 amino acid residues in length

6

since there are 3 genes for MHC class I molecules and each individual inherits one set of genes from Mom and one from Dad, any nucleated cell will express ____ distinct class I molecules

MHC Class 1 molecule

the CD8 receptor recognizes the MHC Class ____ molecule

CDR 1 and 2

the CDR _____ and ______ regions recognize and bind the a helices of the MHC

CDR 3

the CDR that binds the processed Ag

a chain (Class I)

the HLA A, B, and C genes code for an ____ chain which contains 3 globular domains external to the cell membrane, a transmembrane segment, and a cytoplasmic tail

CD4

the MHC class II molecule is recognized by the ____ receptor

chromosome 6

the MHC genes are found on chromosome ____ in humans

chromosome 17

the MHC genes are found on chromosome ____ in mice

MHC antigens

the MHC proteins were orginally defined in relationship to tissue rejecion. MHC molecules are structurally unique to each individual. MHC molecules on tissue cells will be recognized as foreign by a recipient's immune system in a tissue transplant. For this reason, they are often called ____________

T cell

the ______ cell discriminates between self and non-self via the specificity of the TCR

gamma chain

the ____________ chain is hydrolyzed off the Ag-binding grove, Ag is associated, and the Ag-loaded molecule is transported in a vesicle to the cell surface where it is expressed

B cells, MACs, and dendritic cells

the class II molecule is normally found on antigen-presenting cells: _____________, ______________, _______________

MHC Class I

the genes for this molecule are in the HLA-A, HLA-B, and HLA-C regions of the complex. The molecules produced by these genes are found on essentially all nucleated cells

12-16 amino acids

the optimal length of amino acids is?

T cell epitopes

these are often hydrophobic or aromatic peptide fragments

MHC genes

these genes code for the expression of cell surface proteins that function, among other things, to present antigen

amino acid residues

this variability is in _____________________ residues in the a helices and the B pleated sheet

binding specificity

variability in the amino acid sequence of the a1 and B1 domains accounts for ____________________________

invariant chain

when first assembled intracellularly, there is a gamma or _________________ that occupies the antigen-binding site and prevents self antigens from binding