CD4 and CD8 IHC in lung transplant rejection diagnosis and grading. Tissue sections were immnunohistochemically stained with CD4 and CD8 antibodies and showed contrast against the background. A: grade A1 rejection; B: grade A2 rejection; C: grade A3 rejection; D: grade A4 rejection. (x200).T cell immunohistochemistry refines lung transplant acute rejection diagnosis and grading. Cheng L, Guo H, Qiao X, Liu Q, Nie J, Li J, Wang J, Jiang K - Diagnostic pathology (2013). Not Altered. CC.