IgGIgDIgEIgAIgM Bone marrow gives rise to B cells. Mature B cells migrate to lymphoid organs. A mature B cells recognizes epitopes. Clonal Selection.
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IgG IgD IgEIgAIgM
• Bone marrow gives rise to B cells.
• Mature B cells migrate to lymphoid organs.
• A mature B cells recognizes epitopes.
Clonal Selection
Hallmarks of the
Immune Response
• Self/Non-self Discrimination
• Memory
• Specificity
A. Self/non-self discrimination - One characteristic feature of the specific immune system is that it normally distinguishes between self and non-self and only reacts against non-self.B. Memory - A second feature of the specific immune response is that it demonstrates memory. The immune system "remembers" if it has seen an antigen before and it reacts to secondary exposures to an antigen in a manner different than after a primary exposure. Generally only an exposure to the same antigen will illicit this memory response.C. Specificity - A third characteristic feature of the specific immune system is that there is a high degree of specificity in its reactions. A response to a particular antigen is specific for that antigen or a few closely related antigens
T-independent Antigens
Figure 17.17
B cell
Self-tolerance
• Body doesn't make Ab against self
• Clonal deletion
–The process of destroying B and T cells that react to self antigens
T-Dependent Antigens
Figure 17.16
Clonal Selection
Cellular Events in 1o Response to
T-dependent Ags• Lag
– Clonal selection
• Log– IgM– Class switching
• Stationary
• Decline
• Memory Cell Pool
IgM
Memory Cells
IgG
1o Ag
Cellular Events in 2o Response to
T-dependent Ags• Lag phase– Virgin cells– Memory cells
• Log phase– Pool size– IgG, IgA or IgE
• Stationary
• Decline– Sustained
production
IgM
Memory Cells
IgG
IgG
Memory Cells
Memory Pool
Virgin B cell
Memory T cells
Th
Memory Cells
Th
Th
Memory Cells
Memory Pool
Virgin cell
• T Cells– Virgin cells– Memory cells
• Th cells– Cytokines
• Long Term Memory
Animation of cell selection
TORTORA • FUNKE • CASE
Immunoglobulin Genetics
IgG IgD IgEIgAIgM
How many types of Abs???
•100 Millions
•100,000,000 = 108
Immunoglobulin GeneticsHistory
• Same C region could associate with many V regions– IgG Ab with different specificities
• Same V region could associate with many C regions– Same idiotype on IgG and IgM Ab
• V and C regions coded for by separate genes
Light Chain Gene FamiliesGerm line gene organization
J1 C1
E
J2 C2
E
J3 C3
E
J4 C4
EP
L V1
P
L Vn
P
L V2
Lambda light chain genes; n=30
P
L V 1
P
L V n
P
L V 2 J2 J3 J5 C
E
J1 J4
Kappa light chain genes; n=300
Light Chain Gene FamiliesGene rearrangement and expression
L V 1 L V nL V 2 J2 J3 J5 CJ1 J4
DNAP PP E
P P E
L V 1 L J5 C
V 2 J4
DNA
DNA Rearrangement
V CJ
V C
Protein
Transport to ER
Protein
TranslationCL V J
E
L V CJ
RNA
Transcription
Primary transcript
CL V JRNA Processing
RNAmRNA
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