How do each of the following prolong graft survival?
a. antibody to CD4
b. blockade of the interaction between B7 and CD28
c. total lymphoid irradiation
CD4 T cells recognize MHC class II molecules, which are not expressed on the majority of the cells in the graft, but are expressed on any professional antigen presenting cells, such as dendritic cells and macrophages, that are present in the grafted tissue. Some of the host CD4 T cells will recognize the donor MHC class II as 'foreign' and become activated. In addition, host antigen presenting cells will take up proteins released from ...
This solution explains the reasons why certain commonly used strategies for immune suppression are effective at prolonging graft survival. The strategies concerned are: (1) antibodies to CD4, (2) blockade of B7/CD28 interactions, and (3) total lymphoid irradiation.