Subtle differences in CTL cytotoxicity determine susceptibility to hemophagocytic lymphohistiocytosis in mice and humans with Chediak-Higashi syndrome.

Perforin-mediated cytotoxicity is important for controlling viral infections, but also for limiting immune reactions. Failure of this cytotoxic pathway leads to hemophagocytic lymphohistiocytosis (HLH), a life-threatening disorder of uncontrolled T-cell and macrophage activation. We studied susceptibility to HLH in 2 mouse strains (souris and beige(J)) and a cohort of patients with partial defects in perforin secretion resulting from different mutations in the LYST gene. Although both strains lacked NK-cell cytotoxicity, only souris mice developed all clinical and histopathologic signs of HLH after infection with lymphocytic choriomeningitis virus. The 2 strains showed subtle differences in CTL cytotoxicity in vitro that had a large impact on virus control in vivo. Whereas beige(J) CTLs eliminated lymphocytic choriomeningitis virus infection, souris CTLs failed to control the virus, which was associated with the development of HLH. In LYST-mutant patients with Chediak-Higashi syndrome, CTL cytotoxicity was reduced in patients with early-onset HLH, whereas it was retained in patients who later or never developed HLH. Thus, the risk of HLH development is set by a threshold that is determined by subtle differences in CTL cytotoxicity. Differences in the cytotoxic capacity of CTLs may be predictive for the risk of Chediak-Higashi syndrome patients to develop HLH.

Disorders of neutrophil function: an overview.

Primary disorders of neutrophil function result from impairment in neutrophil responses that are critical for host defense. This chapter summarizes inherited disorders of neutrophils that cause defects in neutrophil adhesion, migration, and oxidative killing. These include leukocyte adhesion deficiencies, actin defects, and other disorders of chemotaxis; hyperimmunoglobulin E syndrome; Chédiak-Higashi syndrome; neutrophil specific granule deficiency; chronic granulomatous disease; and myeloperoxidase deficiency. Diagnostic tests and treatment approaches are also summarized for each neutrophil disorder.

Hermansky-Pudlak syndrome and Chediak-Higashi syndrome: disorders of vesicle formation and trafficking.

The rare autosomal recessive metabolic disorders Hermanky-Pudlak syndrome (HPS) and Chediak-Higashi syndrome (CHS)share the clinical findings of oculocutaneous albinism and a platelet storage pool deficiency. In addition, HPS exhibits ceroid lipofuscinosis and CHS is characterized by infections and an accelerated phase. The two disorders result from defects in vesicles of lysosomal lineage. Of the two known HPS-causing genes, HPS1 has no recognizable function, while ADTB3A codes for a subunit of an adaptor complex responsible for new vesicle formation from the trans-Golgi network. Other HPS-causing genes are likely to exist. The only known CHS-causing gene, LYST, codes for a large protein of unknown function. In general, HPS appears to be a disorder of vesicle formation and CHS a defect in vesicle trafficking. These diseases and their variants mirror a group of mouse hypopigmentation mutants. The gene productsinvolved will reveal how the melanosome, platelet dense body, and lysosome are formed and trafficked within cells.

Síndrome de Chediak-Higashi: relato de caso e revisäo da literatura / Chediak-Higashi syndrome: report of one case and literature review

A síndrome de Chediaki-Higashi (SCH) é distúrbio raro, de caráter autossômico recessivo, caracterizada poralbinismo parcial e imunodeficiência celular com presença de grânulos gigantes nos leucócitos e outras células. Os autores apresentam um caso típico, com revisäo da literatura sobre etiologia, patogenia, evoluçäo, diagnóstico clínico laboratorial, diagnóstico diferencial e tratamento

Cloning and mapping of human Rab7 and Rab9 cDNA sequences and identification of a Rab9 pseudogene.

Rab GTPases reside in specific intracellular compartments and are key regulators of vesicular transport. To facilitate studies of the mechanism of lysosomal integral membrane protein (LAMP-1) transport, cDNAs for human Rab7 and Rab9 were isolated, and their nucleotide sequences were determined. During isolation and characterization of these cDNAs a Rab9 pseudogene was identified. The sequences are highly homologous to other mammalian Rab proteins and also share homology with proteins of the Rab GTPase family. Rab7 and the Rab9 pseudogene were mapped to chromosomes 3 and 5, respectively, by amplification of their sequences from human monochromosomal somatic cell hybrids. In addition, preliminary studies using antisense expression indicate that down-regulation of either Rab7 or Rab9 proteins induces severe cell vacuolation that resembles the phenotype seen in fibroblasts from patients with Chediak-Higashi syndrome.

Molecular basis of congenital hypopigmentary disorders in humans: a review.

Many specific gene products are sequentially made and utilized by the melanocyte as it emigrates from its embryonic origin, migrates into specific target sites, synthesizes melanin(s) within a specialized organelle, transfers pigment granules to neighboring cells, and responds to various exogenous cues. A mutation in many of the respective encoding genes can disrupt this process of melanogenesis and can result in hypopigmentary disorders. Following are examples highlighting this scenario. A subset of neural crest derived cells emigrate from the dorsal surface of the neural tube, become committed to the melanoblast lineage, and are targeted along the dorsal lateral pathway. The specific transcription factors PAX3 and MITF (microphthalmia transcription factor) appear to play a regulatory role in early embryonic development of the pigment system and in associated diseases (the Waardenburg syndromes). During the subsequent development and commitment of the melanoblast, concomitant expression of the receptors for fibroblasts growth factor (FGFR2), endothelin-B (EDNRB), and steel factor (cKIT) also appears essential for the continued survival of migrating melanoblasts. Lack or dysfunction of these receptors result in Apert syndrome, Hirschsprung syndrome and piebaldism, respectively. Once the melanocyte resides in its target tissue, a plethora of melanocyte specific enzymes and structural proteins are coordinately expressed to form the melanosome and to convert tyrosine to melanin within it. Mutations in the genes encoding these proteins results in a family of congenital hypopigmentary diseases called oculocutaneous albinism (OCA). The tyrosinase gene family of proteins (tyrosinase, TRP1, and TRP2) regulate the type of eumelanin synthesized and mutations affecting them result in OCA1, OCA3, and slaty (in the murine system), respectively. The P protein, with 12 transmembrane domains localized to the melanosome, has no assigned function as of yet but is responsible for OCA2 when dysfunctional. There are other genetically based syndromes, phenotypically resembling albinism, in which the synthesis of pigmented melanosomes, as well as specialized organelles of other cell types, is compromised. The Hermansky-Pudlak syndrome (HPS) and the Chediak-Higashi syndrome (CHS) are two such disorders. Eventually, the functional melanocyte must be maintained in the tissue throughout life. In some cases it is lost either normally or prematurely. White hair results in the absence of melanocytes repopulating the germinative hair follicle during subsequent anagen stages. Vitiligo, in contrast, results from the destruction and removal of the melanocyte in the epidermis and mucous membranes.

[Primary disorders of neutrophils: principal clinical and laboratory aspects]. / Disfunções primárias de neutrófilos: principais aspectos clínicos e laboratoriais.

This article presents a review of different categories of inherited neutrophil dysfunctions, such as chronic granulomatous disease, disorders of chemotaxis, defects of degranulation and the leukocyte adherence deficiency. The clinical manifestations and laboratory findings of these phagocyte abnormalities, with particular reference to various tests of neutrophil functions used for diagnostic elucidation are described.

[The accelerated phase of Chediak-Higashi syndrome]. / Phase accélérée de la maladie de Chediak-Higashi.

We have retrospectively analysed the clinical and biological features as well as the outcome of 18 accelerated phases having occurred in 11 patients with the Chediak-Higashi syndrome. This complication is very frequent and is characterized by a multi-visceral lymphohistiocytic infiltration with hemophagocytosis leading to pancytopenia, a bleeding disorder secondary to low fibrinogen level, hypertriglyceridemia and hemodilution. The accelerated phase of the Chediak-Higashi syndrome is identical to the manifestations of familial erythrophagocytic lymphohistiocytosis and of the viral-associated hemophagocytic syndrome. The outcome was invariably fatal before the use of etoposide (VP 16) in association with steroids and intrathecal methotrexate. Complete remission with this management regimen was observed in 7/7 cases. However, remissions were only transient. HLA identical bone marrow transplantation appeared to be the only therapeutic strategy capable of curing the disease (3/3 patients). Non transplanted patients relapsed and died as well as one patient who received a HLA non identical bone marrow transplantation. Due to the frequency and the severity of the accelerated phase of the Chediak-Higashi syndrome, HLA identical bone marrow transplantation should be proposed as early as possible after the onset of the accelerated phase.

The role of lysosomes in the pathogenesis of copper-induced hepatotoxicity: morphological studies.

Copper-induced hepatotoxicity was evaluated in beige and conventional mice which were injected intraperitoneally with aqueous copper chloride (8 mg per kg body weight per day). Hepatic lesions developed more quickly and were more severe in beige mice and consisted of karyomegaly, progressive accumulation of lipofuscin within hepatocytes and Kupffer cells, acute necrosis of random hepatocytes, and aggregation of leukocytes within the sinusoids. In both groups of mice the hepatic lesion had a centrilobular distribution and closely paralleled the appearance and distribution of copper within hepatocytes. Overall, beige mice had more severe copper-mediated hepatotoxicity, suggesting that normal lysosomes have protective effects for hepatocytes by sequestering copper from other cytoplasmic constituents.

[Pathology of the polymorphonuclears in dermatology. Methods of investigation. Clinical pictures (author's transl)]. / La pathologie du polynucléaire en dermatologie: moyens d'exploration, aspects cliniques.

A remarkable increase in the number of recognized clinical abnormalities of neutrophil function has occurred within the 8 years past. Of major importance in the delineation of these disorders is the establishment of appropriate methodology of their characterization. This review discusses phagocytosis and its disorders by dividing it into stages that encompass the way in which phagocytes ferret out injection, how they recognize pathogens and the intracellular events leading to engulfment and killing of micro-organisms. The pathology of chemotaxis and random mobility is described: the lazy leukocyte syndrome, the Chediak-Higashi syndrome, the familial chemotaxis pecular dermatosis, and a variety of serum abnormalities of the serum complement system associated with deficient generation of chemotactic activity. The second part of these disorders is dailing with the inherited abnormalities of the oxygen dependent killing mechanisms of phagocytes, the chronic granulomatous disease, the glucose-6-phosphate deshydrogenase deficiency, the myeloperoxydase deficiency and the glutathione peroxydase deficiency.