Immunologie DT2
HC5: B -CELL DEVELOPMENT AND PRODUCTION OF ANTIBODIES
B-cells make antibodies = humoral immunity.
How are extra- and intra cellular pathogens attacked by the adaptive immune system?
Helper T-cells cytotoxic T-cells
Helper T-cells B-cell plasma cell
The adaptive immune system depends on lymphoid organs.
- Primary lymphoid organs: Generation of lymphocytes (bone marrow/thymus)
- Secondary lymphoid organs: Filter of lymph fluid/cells that drains from tissues.
Activation of lymphocytes, lymph nodes, spleen, peyer’s patches.
B-cells
- Generation: Bone marrow
- Many specificities
- Every cell had unique receptor
- Humoral response, antibodies, memory cells.
B-cells recognize intact antigen.
Clonal selection: expansion of B-cell clones that recognize antigen. Differentiation in effector
cells.
B-cell and T-cell receptors are the very specific receptors of the adaptive immune system:
every cell has an unique receptor consisting of variable and constant regions.
- Immunoglobulin = antibody or BCR
- Antibody = secreted form
- BCR = membrane form
, De BCR is identical to the secreted antibody. Recognition and effector
molecules are identical: BCR-antibody.
Structure of immunoglobulin G (IgG)
- Every BCR is different in the variable region
- The constant region is the same
- The hinge region enables flexibility in IgG
An antibody recognizes an epitope on an antigen. An antigen with
multiple epitopes is an multivalent antigen.
Antibodies recognize proteins, carbohydrates, DNA, or small
molecules. Differences in chemical interactions define the strength of
interaction or affinity of an antibody. Antibodies recognize many
different structures.
- The affinity is the strength of a single interaction.
- The avidity is the combined strength of multiple interaction sites.
De CDR regions of the variable domain are most diverse. Differences in amino acid sequence
in variable domains are concentrated in 3 regions
- Hypervariabele regions (HV)
- Complementarity-Determining Regions (CDRs)
- The other regions are much less variable: Framework regions
Different immunoglobulin isotypes or classes:
5 different heavy chains: the constant part provides different effector functions to the Ig.
The variable domains mediate the specificity for the antigen recognized.
- IgG: Most frequent isotype in serum and has the longest half-life.
- IgM: activation of the complement system
- IgD: Sensitization of basophils
- IgA: Transport across epithelium
- IgE: Activation for mastcells (allergies)
Neutralization and opsonization are the two most important effector mechanisms of
antibodies.
- Neutralization: blocks binding and prevents infection
- Opsonization: pathogen gets tagged and receptors recognize the tag and kills the
pathogen.
Antibodies can be:
HC5: B -CELL DEVELOPMENT AND PRODUCTION OF ANTIBODIES
B-cells make antibodies = humoral immunity.
How are extra- and intra cellular pathogens attacked by the adaptive immune system?
Helper T-cells cytotoxic T-cells
Helper T-cells B-cell plasma cell
The adaptive immune system depends on lymphoid organs.
- Primary lymphoid organs: Generation of lymphocytes (bone marrow/thymus)
- Secondary lymphoid organs: Filter of lymph fluid/cells that drains from tissues.
Activation of lymphocytes, lymph nodes, spleen, peyer’s patches.
B-cells
- Generation: Bone marrow
- Many specificities
- Every cell had unique receptor
- Humoral response, antibodies, memory cells.
B-cells recognize intact antigen.
Clonal selection: expansion of B-cell clones that recognize antigen. Differentiation in effector
cells.
B-cell and T-cell receptors are the very specific receptors of the adaptive immune system:
every cell has an unique receptor consisting of variable and constant regions.
- Immunoglobulin = antibody or BCR
- Antibody = secreted form
- BCR = membrane form
, De BCR is identical to the secreted antibody. Recognition and effector
molecules are identical: BCR-antibody.
Structure of immunoglobulin G (IgG)
- Every BCR is different in the variable region
- The constant region is the same
- The hinge region enables flexibility in IgG
An antibody recognizes an epitope on an antigen. An antigen with
multiple epitopes is an multivalent antigen.
Antibodies recognize proteins, carbohydrates, DNA, or small
molecules. Differences in chemical interactions define the strength of
interaction or affinity of an antibody. Antibodies recognize many
different structures.
- The affinity is the strength of a single interaction.
- The avidity is the combined strength of multiple interaction sites.
De CDR regions of the variable domain are most diverse. Differences in amino acid sequence
in variable domains are concentrated in 3 regions
- Hypervariabele regions (HV)
- Complementarity-Determining Regions (CDRs)
- The other regions are much less variable: Framework regions
Different immunoglobulin isotypes or classes:
5 different heavy chains: the constant part provides different effector functions to the Ig.
The variable domains mediate the specificity for the antigen recognized.
- IgG: Most frequent isotype in serum and has the longest half-life.
- IgM: activation of the complement system
- IgD: Sensitization of basophils
- IgA: Transport across epithelium
- IgE: Activation for mastcells (allergies)
Neutralization and opsonization are the two most important effector mechanisms of
antibodies.
- Neutralization: blocks binding and prevents infection
- Opsonization: pathogen gets tagged and receptors recognize the tag and kills the
pathogen.
Antibodies can be:
