i wasn't able to clear up the transplant rejection concept. I know that hyperacute rejection is type II HSN and graft vs host is type IV HSN. What about acute and chronic rejection? What type of HSN are they under? If anyone can clear up, thanks in advance.

hyper acute is due to preformed antibodies
acute is in months n it is cell mediated i.e cytotoxic T cells react against the grafts MHC. so its type 4
chronic is mediated by antibodies made against grafts vasculature.that makes it type 2 i think.

Yea that is wat i thought too. However, UW questions on these dont seem to seperate or classify Acute and Chronic via HSN type. They jz mentioned that Acute is usually 2 weeks post-transplant and host T-cells against graft tissue. Mean while chronic is both B/T cells of host against graft and usually months to years post-transplant. I look at couple different books also but no mention definitively about them. On the other hand since acute using CD8 cells to reject graft tissue, why is not type II (Cytotoxic)? That is why i wasnt clear on this. Thanks for your inputs.