Question

As thymocytes develop, they are classified on the basis of the state of their T-cell receptors and which of the following?

1) Which class of MHC they express on their surface
2) The state of the immunoglobulin heavy and light chains on their surface
3) The presence of coreceptor proteins CD4 and CD8 on their surface
4) The expression of the transcription factor, FoxP3
5) None of the above

Answer 1

Thymocytes are classified based on the state of their T-cell receptors and the presence of coreceptor proteins CD4 and CD8 on their surface. The cells that leave the thymus express either CD4 or CD8, but not both. CD4+ T cells bind to class II MHC, while CD8+ cells bind to class I MHC. Hence the correct answer is option 3

Step-by-step explanation:

As thymocytes develop, they are classified on the basis of the state of their T-cell receptors and the presence of coreceptor proteins CD4 and CD8 on their surface. The cells that leave the thymus become single positives, expressing either CD4 or CD8, but not both. CD4+ T cells will bind to class II MHC, while CD8+ cells will bind to class I MHC. The expression of the transcription factor, FoxP3, is not used for classification of thymocytes.

Hence the correct answer is option 3