IgG IgM IgA IgD IgE

Bone marrow gives rise to B cells. Clonal Selection Bone marrow gives rise to B cells. Mature B cells migrate to lymphoid organs. A mature B cells recognizes epitopes.

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 B cell Figure 17.17

Body doesn't make Ab against self Clonal deletion 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 Memory Pool Virgin B cell

Memory T cells T Cells Th cells Long Term Memory Virgin cells Memory cells Th cells Cytokines Long Term Memory Th Memory Cells Memory Pool Virgin cell

Animation of cell selection

Immunoglobulin Genetics

IgG IgM IgA IgD IgE

How many types of Abs??? 100 Millions 100,000,000 = 108

Immunoglobulin Genetics History 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 Families Germ line gene organization J1 C1 E J2 C2 J3 C3 J4 C4 P L V1 Vn V2 Lambda light chain genes; n=30 P L V  1 V  n V  2 J2 J3 J5 C E J1 J4 Kappa light chain genes; n=300

Light Chain Gene Families Gene rearrangement and expression V 1 V n V 2 J2 J3 J5 C J1 J4 DNA P E P E L V 1 J5 C V 2 J4 DNA DNA Rearrangement E L V C J RNA Transcription Primary transcript C L V J RNA Processing RNA mRNA Protein Translation C L V J V C J Protein Transport to ER