Immune Recognition II: Adaptive Receptors Flashcards Preview

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Flashcards in Immune Recognition II: Adaptive Receptors Deck (22):
1

what are the three types of adaptive receptors?

immunoglobulins
t cell receptors
antigen presenting molecules

2

immunoglobulins: what produces them, transmembrane/secreted?, what Ag do they recognize?

B cells

transmembrane (B cell receptors) or secreted (immunoglobulins or Ab)

3D surface of proteins, lipids, sugars, nucleic acids, mixture

3

T cell receptors: what produces them, transmembrane/secreted?, what Ag do they recognize?

T cells

transmembrane

linear fragments of proteins presented on surface of APC

4

antigen presenting molecules: what produces them, transmembrane/secreted?, what Ag do they recognize?

APC (dendritic cells)

transmembrane

bind peptides and present them at cell surface via MHC or HLA molecules for recognition by TCR

5

Describe recombination with respect to Ag receptor synthesis/variability.

Different V, D, and J regions are combined and random nucleotides are introduced or changed at the junctions between the segments

the variable region is combined with a constant gene segment (maintain signal transduction/effector fxns)

6

Give the general structure of immunoglobulins

heavy and light chain with variable and constant region

light+heavy heterodimer (disulfided linked) joins to another to form a homodimer (disulfide linked)

can be soluble or have a transmembrane/cytoplasmic domain

7

what is the Ag binding site?

light chain domain+heavy chain domain

so two identical Ag binding sites on one immunoglobulin

8

What does the constant region do?

support Ag binding site

provide interchain disulfide bonds

hinge region allows flexability

Fc fragment has effector fxns, sites for association w/ other molecules for transmission of signals after Ag recognition

9

What are the five classes of Immunoglobulin isotypes

IgD
IgG
IgE
IgA
IgM

10

Distinguish between the Ig isotypes based off structure

IgD - membrane bound
IgG - three heavy domains
IgE - four heavy domains
IgA - a dimer of two Ig
IgM - pentamer of 5 Ig

11

What are different effector functions of Ig isotypes?

neutralization (block viral particles or toxins from acting)

opsonization (promote phagocytosis)

complement fixation (leading to C3 cleavage)

The Fc region imparts the effector fxn

Activate Fc receptor+ cells (NK, mast) to to respond (cytolysis, histamine release)

12

Describe general TCR structure

heterodimers (alpha/beta or gamma/delta)

chains linked via disulfide bond

variable and constant domain

always membrane bound

13

What types of Ag do TCRs recognize?

linear peptide of 8-16 polypeptides presented by MHC

recognizes both the peptide and the MHC 3D surface

14

what is the CD3 complex?

TCR are always expressed at surface with 4 other transmembrane proteins

fxn - aids in activating intracellular signaling cascades

15

does BCR act alone?

No.

Igbeta and Igalpha are two signaling subunits associated with Ig.

16

does a single receptor binding lead to signal transduction?

No.

Ag binding brings brings BCR and TCR together in clusters on cell surface leading to actiavtion of cytoplasmic signaling cascades that lead to translocation of trxn factors to nucleus

17

what expresses MHC I

all cells except RBC and neurons

18

what expresses MHC II

only those that interact with T cells

dendritic cells, macrophages, monocytes, B cells

19

what is the fxn of MHC molecules?

bind peptide fragments and present them on surface of APCs for T cells to recognize

20

MHC I/II vs. intracellular/extracellular

MHC I = intracellular pathogen source

MHC II = extracellular pathogen source

21

match up the CD4/8 to the MHC I/II

CD4+ T cells are MHC II restricted
CD8+ T cells are MHC I restricted

22

Each individual has multiple HLA genes and there are hundreds of different alleles in the population. What two things does this have an impact on?

1. Transplantation
2. Disease resistance and susceptibility