title: The functional basis for hemophagocytic lymphohistiocytosis in a patient with co-inherited missense mutations in the perforin (PFN1) gene.
abstract: About 30% of cases of the autosomal recessive immunodeficiency disorder hemophagocytic lymphohistiocytosis are believed to be caused by inactivating mutations of the perforin gene. We expressed perforin in rat basophil leukemia cells to define the basis of perforin dysfunction associated with two mutations, R225W and G429E, inherited by a compound heterozygote patient. Whereas RBL cells expressing wild-type perforin (67 kD) efficiently killed Jurkat target cells to which they were conjugated, the substitution to tryptophan at position 225 resulted in expression of a truncated ( approximately 45 kD) form of the protein, complete loss of cytotoxicity, and failure to traffic to rat basophil leukemia secretory granules. By contrast, G429E perforin was correctly processed, stored, and released, but the rat basophil leukemia cells possessed reduced cytotoxicity. The defective function of G429E perforin mapped downstream of exocytosis and was due to its reduced ability to bind lipid membranes in a calcium-dependent manner. This study elucidates the cellular basis for perforin dysfunctions in hemophagocytic lymphohistiocytosis and provides the means for studying structure-function relationships for lymphocyte perforin.
authors.affiliation: Cancer Immunology Program, Peter MacCallum Cancer Centre, Locked Bag 1, A'Beckett St., 8006, Australia.
authors.forename: Ilia
authors.initials: I
authors.lastname: Voskoboinik
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Thia
authors.forename: Annette
authors.initials: A
authors.lastname: De Bono
authors.forename: Kylie
authors.initials: K
authors.lastname: Browne
authors.forename: Erika
authors.initials: E
authors.lastname: Cretney
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Jackson
authors.forename: Phillip K
authors.initials: PK
authors.lastname: Darcy
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Jane
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Smyth
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Trapani
mesh_terms: D000818:Animals; D015616:Histiocytosis, Non-Langerhans-Cell / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D020125:Mutation, Missense; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D051381:Rats; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin