A researcher recently found 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 was his findings?
2) He next made bone marrow chimeras, injecting the bone marrow from HD mice within the lethaly irradiated wildtype mice. They found that thymocytes in these chimeras exhibited a staining pattern identical to that of HD mice. Incontrast when they did the inverse, they found that the thymocytes exhibited a normalCD4/CD8 phenotype. What do these results tell you?
3) On the basis of these results, advance a hypothesis regarding the cause of the phenotype.
4) On the basis of your hypothesis, what do you predict would occur to developing T cell in an HD mouse which has been made transgenic for a TCR restricted to I- Ab. Describe your reasoning.