Natural killer cells do not mediate facial motoneuron survival after facial nerve transection

The goal of the current study was to determine if natural killer (NK) cells mediate facial motoneuron (FMN) survival following injury. Wild-type (WT), perforin/recombinase activating gene-2 knockout (pfp/RAG-2 KO), and common gamma-chain (gammac)/RAG-2 KO mice received a right facial nerve axotomy. In WT mice, FMN survival was 86 +/- 1.0% relative to the contralateral control side. In contrast, pfp/RAG-2 and gammac/RAG-2 KO mice exhibited significant decreases in FMN survival (similar to20% and similar to30%, respectively), relative to WT. Reconstitution of pfplRAG-2 and gammac/RAG-2 KO mice with normal NK cells alone, failed to restore FMN survival levels to those of WT, but did restore functional lytic activity against YAG-1 cells. Reconstitution of pfp/RAG-2 and gammac/RAG-2 KO mice with splenocytes, and pfp/RAG-2 KO mice with CD4(+) T-lymphocytes alone or in combination with NK cells, restored FMN survival levels to those of WT. Thus, NK cells appear to not be a component of immune cell-mediated rescue of motoneurons from axotomy induced cell death. (C) 2003 Elsevier Science (USA). All rights reserved.