A patient receives a kidney transplant but develops acute rejection within days despite initial HLA matching. Which mechanism most directly explains this rapid rejection despite immunosuppression?

💡 Explanation

T cell allorecognition via the direct pathway causes acute rejection because donor antigen-presenting cells migrate to host lymphoid organs, stimulating a strong T cell response that bypasses some immunosuppressants. Therefore, T cell allorecognition causes this acute rejection, rather than innate immunity or antibody-mediated responses, which take longer to develop.

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