Natural Killer T Cells Contribute to Neutrophil Recruitment and Ocular Tissue Damage in a Model of Intraocular Tumor Rejection.

PURPOSE: Immune privilege of the eye protects the nonregenerative ocular tissues from innate and adaptive immune-mediated inflammation. In the case of intraocular tumors, immune privilege can be arrested to allow for immune-mediated rejection. Activation of innate immune cells can contribute to necrosis of the intraocular tumor and bystander ocular tissue. Identifying the cellular components of the innate immune system that contribute to ocular destruction, but are not needed for tumor rejection, provides insights into the immunopathological sequelae in intraocular tumor rejection.

METHODS: Wild-type (WT), Jα18 knockout (KO) mice lacking type I natural killer T (NKT) cells, and CD1d KO mice lacking all NKT cells, were used to identify the role of type II NKT cells in intraocular tumor rejection immunopathology.

RESULTS: CD1d KO mice had significantly lowered rates of necrotic eye destruction during tumor rejection compared to WT or Jα18 KO mice. Transcriptome and protein analyses revealed that CD1d KO mice had significantly lower expression of CXCL3 compared to WT or Jα18 KO mice, and this was associated with decreased neutrophil recruitment. The presence of type II NKT cells in WT or Jα18 KO mice led to increased CXCL3, which attracted neutrophils to the intraocular tumor and culminated in destruction of the eye.

CONCLUSIONS: We found that type II NKT cells are critical in initiating a damaging inflammatory antitumor response involving the recruitment of neutrophils that compromises the integrity of the eye. Loss of type II NKT cells or depleting neutrophils allows for a productive intraocular tumor response that converts the rejection phenotype to preserve the eye.