A researcher recently finds out a mutant mouse with an interesting T cell phenotype. He called this new mutation: HD," bred the mouse and then used these founders to produce a strain homozygous for HD. Some of his findings are summarized in the table below:
|
|
Thymocytes
|
Lymph node t cells
|
|
|
CD4+8+
|
CD4+
|
CD8+
|
CD4+
|
CD8+
|
|
Wild typ
|
100
|
40
|
20
|
20
|
12
|
|
HD mutant
|
100
|
1
|
20
|
0.5
|
14
|
1) What did he determine?
2) He next made the bone marrow chimeras, injecting the bone marrow from HD mice into the lethaly irradiated wildtype mice. They discovered that thymocytes within these chimeras exhibited a staining pattern similar to that of HD mice. Incontrast when they did the inverse, they determine that the thymocytes exhibited a normalCD4/CD8 phenotype. What do these results tell you?
3) On the basis of these results, advance a hypothesis about the cause of the phenotype.
4) Based on your hypothesis, what do you predict would happen to developing T cell in an HD mouse which has been made transgenic for a TCR restricted to I- Ab. Explain your reasoning.