Lymphoid tissue formation in allografts: innocent until proven guilty.

Tertiary lymphoid organs (TLOs) are lymphoid-like structures commonly found at sites of chronic inflammation. Commonly associated with autoimmune responses, they have recently been described within organ allografts. Although TLOs are similar structurally to secondary lymphoid organs, their function remains largely unknown. In this review, we discuss how immune responses within TLOs may influence graft survival.