title: Temperature sensitivity of human perforin mutants unmasks subtotal loss of cytotoxicity, delayed FHL, and a predisposition to cancer.
abstract: The pore-forming protein perforin is critical for defense against many human pathogens and for preventing a catastrophic collapse of immune homeostasis, manifested in infancy as Type 2 familial hemophagocytic lymphohistiocytosis (FHL). However, no evidence has yet linked defective perforin cytotoxicity with cancer susceptibility in humans. Here, we examined perforin function in every patient reported in the literature who lived to at least 10 years of age without developing FHL despite inheriting mutations in both of their perforin (PRF1) alleles. Our analysis showed that almost 50% of these patients developed at least 1 hematological malignancy in childhood or adolescence. The broad range of pathologies argued strongly against a common environmental or viral cause for the extraordinary cancer incidence. Functionally, what distinguished these patients was their inheritance of PRF1 alleles encoding temperature-sensitive missense mutations. By contrast, truly null missense mutations with no rescue at the permissive temperature were associated with the more common severe presentation with FHL in early infancy. Our study provides the first mechanistic evidence for a link between defective perforin-mediated cytotoxicity and cancer susceptibility in humans and establishes the paradigm that temperature sensitivity of perforin function is a predictor of FHL severity.
authors.affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, St Andrew's Place, East Melbourne, Victoria 3002, Australia.
authors.forename: Jenny
authors.initials: J
authors.lastname: Chia
authors.forename: Kim Pin
authors.initials: KP
authors.lastname: Yeo
authors.forename: James C
authors.initials: JC
authors.lastname: Whisstock
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Dunstone
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Trapani
authors.forename: Ilia
authors.initials: I
authors.lastname: Voskoboinik
mesh_terms: D000483:Alleles; D020022:Genetic Predisposition to Disease; D006801:Humans; D051359:Lymphohistiocytosis, Hemophagocytic / Q000276:immunology*; D020125:Mutation, Missense; D054353:Perforin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017510:Protein Folding; D013696:Temperature
chemical_list: D054353:Perforin