DadooKhan
Forum Junior
Topics: 11
Posts: 50
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1) first injection -- is the first response -- has a long lag phase, and IgM's will be made. Second injection -- secondary response -- shorter lag phase, and high titer IgG is the predominant response (??and also some IgM but much less??)
2)
--> First you have germ line diversity -- VDJ gene duplication
--> Then you have combinatorial diversity (using RAG1/RAG2 enzymes) -- DJ followed by VDJ heavy chain recombination
--> Junctional diversiyt : TdT enzyme -- point addition/deletion of nucleotides (kinda like filling in the gap)
--> Light chain gene arrangement -- VJ rearrangement
--> Negative selection and allelic exclusion occur
--> mature B-cell with Ig molecules.
--> At this point the B cell leaves the bone marrow (the primary tissue)
--> Once at the secondary tissue (lymph node, or other lymphoid organs) -- there can be modifying of the Ab molecule AFTER Ag exposure -- a process called SOMATIC HYPERMUTATION
I hope this helps. I think it's correct... but anyone plz correct me if I'm wrong.
-DK 
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| smen
Forum Newbie
Topics: 6
Posts: 7
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Thank you very much for helping me with these two questions. I have been struggling with them but now you save my life, hehe. So I can send it to my professor now.
--May--
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| jorgefhoyos
Forum Newbie
Topics: 1
Posts: 48
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I think that's not the answer you were asking for....
If you want to know specifically what happens IN the lymph node, here's a brief description:
the bovine protein antigen is taken up by an antigen presenting cell (macrophage most likely) and it's processed and presented on the surface by a MHC class II molecule. The macrophage makes it's way to a lymph node through an afferent vessel.
The macrophage then presents it to a Th2 cell in the paracortex which is rich in T-cells.
The Thelper 2 cell is now stimulated and starts producing interleukins to stimulate the B cells in the cortical region of the lymph node. B cells are in the cortex in 2 ways, either in the dense and dormant primary folicles or in the active secondary folicles which have a pale active center called the germinal center.
This activation and rapid dividing, makes the germinal centers fill up with B-cells, because of clonal expansion/division and the centers grow, which manifests itself as swelling up of the lymph node.
The B cells and now plasma cells are ready to go into the circulation through the efferent vessel and go to the rest of the RES.
I hope that helps a bit.
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