RESULTS: As expected, isografts showed no obvious signs of rejection, whereas allografts exhibited minimal-to-mild rejection (grade A1-A2) by day 3 and moderate-to-severe rejection (grade A3-A4) by day 7, without evidence of OB. However, by 28 days, evidence of OB was observed in 67% (2/3) of allografts and severe rejection (grade A4) was observed in all. IL-17 mRNA expression in allografts was increased with rejection, and interferon-γ and IL-6 mRNA expression levels followed a similar pattern. In contrast, IL-22 expression in allografts was only slightly increased. Antibody neutralization of IL-17A diminished the signs of acute rejection at 7 days after transplantation in allografts, and this early protection was accompanied by a decrease in cellular stress according to histological evaluation, suggesting the involvement of IL-17A in the development of early post-transplantation lesions. Moreover, increased γδT lymphocyte infiltration, especially Vγ4 γδT cells, was observed in allografts and may represent a source of IL-17A post-transplantation.