What type of immune response is primarily responsible for graft rejection after a homograft?

The immune response primarily responsible for graft rejection after a homograft is mediated by T cells. This type of response is classified as a cell-mediated immune response, which is crucial in recognizing and responding to non-self tissues, such as grafts or transplants.

T cells play a central role in identifying foreign antigens presented by the graft tissue. When a homograft is introduced into a recipient, the T cells recognize the differences in major histocompatibility complex (MHC) molecules between the donor and recipient tissues. This recognition triggers a series of immune reactions, primarily driven by cytotoxic T cells that attack and destroy the foreign cells, leading to rejection.

While B cells, macrophages, and natural killer cells also contribute to the immune response, they do so in different capacities. B cells are primarily responsible for producing antibodies, which are more relevant in humoral immunity rather than direct graft rejection. Macrophages perform functions such as phagocytosis and can help in the presentation of antigens but do not primarily drive the acute rejection process. Natural killer cells play a role in surveillance and clearing of infected or maladaptive cells but are less central to the rejection of allogenic transplants compared to T cells. Thus, the predominant player in the