Figure 1.

Importance of blood and lymphatic vessels in the host bed of high-risk corneas as exit and entry routes of the immune reflex arc for subsequent immunologic graft rejection. (1) Magnification of the host–graft interface: blood (red) and lymphatic vessels (green) reach the host–graft interface. Antigen (Ag) and antigen presenting cells (APCs) both of host and donor can leave the cornea using corneal lymphatics (2), conjunctival lymphatics and then as the afferent arc of the immune response reach the regional lymph nodes (3). After stimulation of alloreactive T lymphocytes, these and other effector cells/antibodies can reach the graft via corneal blood vessels ((4): efferent arc of the immune response). Reproduced from Cursiefen et al. 2003 [48].