Allograft rejection is an example of?
GVHD
Delayed types hypersensitivity
Immediate hypersensitivity
Acute rejection
Ans. (b) Delayed type hypersensitivity(Ref: Robbins 9th/pg 231-234; 8th/pg 221-229; Refer Ans 200)Types of Rejection Pathway:Direct pathway: CD4 and CD8-T cells of the transplant recipient recognize allogeneic (donor) MHC molecules on the surface of APCs in the graft.Indirect pathway: recipient CD4-T lymphocytes recognize MHC antigens of the graft donor after they are presented by the recipient's own APCs.As both the pathways are cell mediated, hence they are delayed hypersensitivity reactions.
Immunity