Immune Study Notes Lecture 8
1. What theory was published in 1957?
Clonal selection theory.
2. What are the unique receptors?
B and T cells are the unique receptors – sometimes these are indistinguishable.
Lymphocytes – cells that make the B and T cells are the units that are selectable.
3. What is the first step of this theory.
Progenitor cells can develop many different types of antibodies that have a wide
variety of receptors which enables them to bind a multitude of different pathogens.
What is unknown is whether or not these variable regions are pre-existing; or if the
adaptive immune system makes new ones as immune response occurs. The second
step is clonal deletion in which those that are self reactive are removed. The
lymphocytes that now are in the body are mature can detect an antigen and start to
proliferate and make many antibodies (expand and differentiate). This pool
recognizes the SAME pathogen.
4. What were the Landsteiner and Chase Experiments?
Converted DNP to KLH.
5. Discuss gene rearrangement.
Genes hae preexisting DNA but they undergo recombination at the DNA level in
order to come up with a variety of surfaces that recognize a variety of pathogens.
RAG1/2 act as V(D)J recombinase enzymes. The DNA is cut at Recombination
Sequence Signals and put back together by DNA repair mechanisms. This happens
with extreme specificity.
6. What are the 3 immunoglobin genes?
IgH = Heavy chain
IgK = kappa light chain
IgL = lambda light chain
At the 5’ end is the variable region and at the 3’ end is the constant region. Within
these regions can be “D” regions = diversity or “J” regions which means joiner.
Leaders are in front of the V regions because they receive them.
7. How many functional gene segments are in each? L = lambda: V=29-33, D=0, J=4-5, C=4-5
K = kappa: V=34-38, D=0, J=5, C=1
H = heavy chain: V=38-46, D=23, J=6, C=9
8. Discuss the 12-23 rule.
The RSS is located on the 3’ end of the V region and the 5’ of the J. In the heavy chain,
the D region has an RSS on both sides. Two signal sequences cannot recombine if
they are the same. There is a heptamer sequence on the 5’ end and a noname