Purpose: To further evaluate the role of draining cervical lymph nodes (CLN) in high-risk (HR) corneal allografts performed in vascularized beds. Recently, we have shown that CLN are critical for promotion of allograft rejection in normal-risk corneal allografts.
Methods: Fully mismatched HR orthotopic corneal transplantation was performed in BALB/c hosts that had their CLN excised before transplantation (CLN-). Graft rejection and allospecific delayed-type hypersensitivity (DTH) were used as measures of alloreactivity. Numbers of interferon gamma (IFN-gamma)- and interleukin 2 (IL-2)-expressing cells were compared among hosts that retained their native CLN (CLN+) and CLN-hosts. Additionally, splenectomized mice (Sp-), and hosts without either CLN or spleen (CLN-Sp-) were evaluated.
Results: Within 5 weeks, 100% of HR grafts among CLN+ hosts were rejected, and hosts of these grafts uniformly demonstrated allospecific delayed-type hypersensitivity (DTH). In contrast, 92% of CLN-hosts accepted their HR allografts, and demonstrated suppressed allospecific DTH response. Moreover, significantly lower numbers of IFN-gamma- and IL-2-expressing cells were infiltrating corneal grafts in CLN-group. All Sp-hosts rejected corneal allografts in an accelerated manner, whereas 86% of CLN-Sp-hosts accepted their allografts indefinitely.
Conclusions: Draining CLN play a critical role in alloimmunity and rejection of HR corneal grafts, suggesting the essential function of CLN in corneal alloimmunization regardless of the degree of preoperative risk. Modulation of factors that regulate access of alloantigens or antigen-laden antigen-presenting cells to draining CLN may offer novel strategies in controlling induction of alloimmunity in corneal transplantation.