True about hyperacute rejection in renal transplant:
**Core Concept**
Hyperacute rejection in renal transplant refers to an immediate and severe immune response against the transplanted kidney, often mediated by pre-existing antibodies against the donor's human leukocyte antigens (HLA). This rejection occurs within minutes to hours after transplant and is a major cause of early graft loss.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of hyperacute rejection, which involves the activation of complement and coagulation pathways. Pre-existing antibodies against the donor's HLA bind to the endothelial cells of the graft, leading to activation of the complement system and coagulation cascade. This results in thrombosis, inflammation, and ultimately, graft failure. The correct answer highlights the key role of complement activation in hyperacute rejection.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the pathophysiology of hyperacute rejection. Hyperacute rejection is not primarily mediated by T cells, but rather by pre-existing antibodies against the donor's HLA.
**Option B:** This option is incorrect because it does not specify the role of complement activation in hyperacute rejection. While inflammation is a component of hyperacute rejection, it is not the primary mechanism.
**Option C:** This option is incorrect because it does not accurately describe the time frame of hyperacute rejection. Hyperacute rejection occurs within minutes to hours after transplant, not days or weeks.
**Option D:** This option is incorrect because it does not specify the role of pre-existing antibodies against the donor's HLA in hyperacute rejection.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that hyperacute rejection is often associated with a positive cross-match between the donor and recipient, indicating pre-existing antibodies against the donor's HLA. This can be detected by pre-transplant cross-matching tests.
**Correct Answer:** C.