Frequency of isolated cutaneous involvement in adult mastocytosis: a cohort study.

BACKGROUND: Mastocytosis is characterized by the accumulation/proliferation of abnormal mast cells. The frequency of isolated cutaneous involvement in adults with mastocytosis has not been fully determined. The main objective of our study was to assess the frequency of isolated cutaneous mastocytosis (CM) in adults with mastocytosis skin lesions. The second objective was to compare the clinical, histological, biological and imaging features in patients with isolated CM and patients with systemic mastocytosis (SM). METHODS: We included all patients with histology-proven mastocytosis skin lesions between January 2009 and December 2017. The mastocytosis diagnosis was made according to the international diagnostic criteria. All data were collected from a dedicated specific case report. RESULTS: Among 160 patients with mastocytosis skin lesions, 25 patients had isolated CM (15.6%), 105 had SM and 30 (18.7%) patients had undetermined mastocytosis. Skin KIT mutation (OR: 51.9, 95% CI: 3.9-678, P = 0.001) and high bone marrow tryptase (OR: 97.4, 95% CI: 10.3-915, P = 0.001) were strong predictors of SM. The prevalence of osteoporosis was higher in the SM population than in the isolated CM population. Moreover, a decrease in bone mineral density over a short period of follow-up (1-2 years) was associated with SM. There were no differences between the two groups regarding the frequency of mast cell activation symptoms, the presentation of skin lesions, the number of mast cells in the dermis and the level of serum tryptase. We propose considering the KIT mutation status and bone marrow tryptase levels to aid the diagnosis of isolated CM in adult mastocytosis patients. CONCLUSION: Only a small minority of adults with mastocytosis skin lesions has isolated cutaneous involvement. In 18.7% of mastocytosis cases, even complete workup does not allow for a precise classification of patients.

Higher prevalence of vertebral fractures in systemic mastocytosis, but not in cutaneous mastocytosis and idiopathic mast cell activation syndrome.

Little is known about osteoporosis in mast cell disorders (MCDs) not related to systemic mastocytosis. We described osteoporosis and fractures in MCDs and showed that systemic mastocytosis was the only studied MCDs associated with osteoporotic vertebral fractures. INTRODUCTION: To describe osteoporosis (OP) and fragility fractures in mast cell disorders (MCDs). METHODS: We retrospectively analyzed data concerning all successive patients with systemic mastocytosis (SM), cutaneous mastocytosis (CM), and mast cell activation syndromes (MCAS) diagnosed in our mastocytosis expert center between 2004 and 2015. We collected data concerning demographic profiles, clinical signs of MCD, osteoporosis, fractures, densitometry, and biological assessment of MCD. We compared CM and MCAS patients with SM patients with regard to the characteristics of OP and fragility fractures. RESULTS: We assessed 89 SM patients, 20 CM patients, and 20 MCAS patients. Osteoporosis was less frequent in CM (15.0%) and MCAS (10.0%) than in SM (44.9%). Similarly, fractures were less frequent in non-SM MCDs, respectively 5.0%, 5.0%, and 28.1%. SM patients displayed high prevalence of vertebral fractures (22.5%), mostly multiple. Conversely, in non-SM patients, vertebral fractures appeared to be uncommon (5%) and more frequently associated with risk factors for osteoporosis. CONCLUSIONS: SM is associated with multiple vertebral osteoporotic fractures, whereas CM and MCAS do not appear to be associated with this phenotype.

Reference values for T, B and NK human lymphocyte subpopulations in adults.

The data presented in this paper are reference ranges for frequencies of thirty-eight subpopulations of T, B and NK lymphocytes, established from a cohort of 253 healthy blood donors aged from 19 to 67. When relevant, the influence of age or sex was taken into account to calculate these reference values. This article is related to the research article entitled "Influence of age, sex and HCMV-serostatus on blood lymphocyte subpopulations in healthy adults" (Apoil et al., 2017) [1]. Immunophenotyping data obtained from each individual is made publicly available for extended analyses.

Influence of age, sex and HCMV-serostatus on blood lymphocyte subpopulations in healthy adults.

Using a standardized immunophenotyping procedure we studied thirty-eight distinct subpopulations of T, B and NK lymphocytes in 253 healthy blood donors aged from 19 to 67. We analysed the influence of age, sex and HCMV seropositivity on each lymphocyte subpopulations and established reference ranges. We observed that aging influences the largest number of lymphocyte subpopulations with a slow increase of CD8+ EMRA T lymphocytes and of the numbers of circulating Tregs. The proportion of HLA-DR+ cells among Tregs increased with age and was correlated to the proportion of HLA-DR+ cells among effector T CD4+ lymphocytes. Sex had a major impact on absolute counts of CD4+ T cells which were higher in females. HCMV-seropositivity was associated with higher frequencies of CD8+ EMRA memory T lymphocytes while a high frequency of terminally differentiated EMRA CD4+ T cells was observed in 80% of HCMV-positive individuals and in none of the HCMV seronegative individuals.

Bone marrow tryptase as a possible diagnostic criterion for adult systemic mastocytosis.

BACKGROUND: Mastocytosis is difficult to diagnose, especially when systemic mast cell activation symptoms are not present or involve only one extracutaneous organ. OBJECTIVE: The main objective was to evaluate the accuracy of the bone marrow tryptase level in the diagnosis of systemic mastocytosis in patients with a clinical suspicion of mastocytosis. METHODS: We included all adult patients evaluated in our centre between December 2009 and 2013 for suspected mastocytosis as part of a standardized procedure and who had a bone marrow and serum tryptase assay on the same day. The diagnosis of systemic mastocytosis was established on the basis of the World Health Organization criteria as the gold standard. The accuracy of the bone marrow tryptase level in the diagnosis of systemic mastocytosis was assessed by a receiver operating characteristics curve analysis. The different sensitivity and specificity values, corresponding to the set of possible bone marrow tryptase level cut-off values, were estimated with 95% confidence intervals. RESULTS: Seventy-three patients were included. The diagnosis of systemic mastocytosis was established in 43 patients (58.9%). The median bone marrow tryptase level was 423 µg/L [95% CI: 217-868] in the systemic mastocytosis group and 7.5 µg/L [95% CI: 4.6-17.1] in the non-systemic mastocytosis group (P < 0.001). A cut-off value of 50 µg/L for bone marrow tryptase identified systemic mastocytosis with a sensitivity of 93.0% [95% CI: 80.9-98.5%] and a specificity of 90.0% [95% CI: 73.5-97.9%]. CONCLUSION AND CLINICAL RELEVANCE: The bone marrow tryptase level appears to be a valuable diagnostic criterion for confirming systemic mastocytosis. If this diagnosis can reliably be excluded by evaluation of the bone marrow tryptase level, there would be no need to perform a bone marrow biopsy.

The importance of EN ISO 15189 accreditation of allergen-specific IgE determination for reliable in vitro allergy diagnosis.

BACKGROUND: Allergen-specific serum immunoglobulin E detection and quantification have become an important step in allergy diagnosis and follow-up. In line with the current trend of laboratory test accreditation to international standards, we set out to design and assess an accreditation procedure for allergen-specific serum IgE. METHODS: Method validation according to the accreditation procedure under the EN ISO 15189 standard was carried out for allergen-specific immunoglobulin E determination using the fluoroimmunoenzymatic method ImmunoCAP(®) (ThermoFisher). Data were produced by 25 hospital laboratories in France. A total of 29 allergen specificities including mixes, extracts, and molecular allergens were assayed. Allergen-specific serum immunoglobulin E concentrations ranged from 0.1 to 100 kUA /l. RESULTS: Repeatability, reproducibility, and accuracy results fulfilled method validation criteria for automated laboratory tests and proved similar irrespective of the allergen specificity, allergen-specific serum immunoglobulin E concentration, or individual laboratory. CONCLUSION: Allergen-specific serum immunoglobulin E determination with the fluoroimmunoenzymatic method ImmunoCAP(®) is a highly repeatable, reproducible, and accurate method which may be considered as a single analyte assay in view of the EN ISO 15189 accreditation procedure.

HIGM syndrome caused by insertion of an AluYb8 element in exon 1 of the CD40LG gene.

A new mutation of the CD40LG gene that encodes the CD40 ligand molecule was characterized in a young patient harboring a hyper-IgM with immunodeficiency syndrome. Inactivation of CD40LG gene resulted from the insertion of an AluYb8 element in exon 1 responsible for a total deficiency of CD40 ligand expression by T lymphocytes. Maternal transmission of the X-linked mutation was confirmed by gene-specific polymerase chain reaction. This is the 17th case report concerning a human genetic disease caused by an Alu element insertion in a coding sequence.

Molecular polymorphism of O alleles in five populations of different ethnic origins.

Sequences of exons 6 and 7 of the O allele of the ABO gene were studied in 317 individuals of the O phenotype from five different ethnic groups (Basques, Berbers, Akans from the Ivory Coast, and Amerindians: Cayapas from Ecuador and Aymaras from Bolivia). Twenty-one O alleles were characterized, among which 9 differed from all O alleles reported to date. The nine alleles differed from either the O01 allele (four out of nine) or O02 allele (five out of nine) by one to three point mutations. The number of different O alleles in population samples varied greatly: the highest number (13) was observed in Akans, and the lowest (5) in Amerindians. Some rare alleles previously reported by others at low frequencies were found with high frequencies in the Akans. The results also revealed a decreasing frequency of Ov7 alleles from south to north (Akans, Berbers, Basques). Berbers and Basques share two rare alleles, Ov6 and O03, which were not encountered in the other populations studied here.

Sequence, organization, and evolution of Rh50 glycoprotein genes in nonhuman primates.

The human RHAG locus encodes Rh50 glycoprotein, a polytopic protein that modulates expression of Rh antigens carried by Rh30 polypeptides. Rh50 is almost invariant, whereas Rh30 shows high polymorphism. To assess the relative conservation and phylogenetic relationship of RHAG genes, we characterized their protein expression, transcript structure, genomic organization, and noncoding regions (promoter and introns) in seven nonhuman primate species. Western blot showed that only ape Rh50 glycoproteins are recognized by the antibody 2D10 specific for the human counterpart. Analysis of RHAG gene and its transcript showed a high degree of sequence identity and features of interspecific diversity. The nonhuman primate RHAG genes are highly similar in promoter region and identical in exon-intron organization. Genomic sequencing identified one retro-transposon-like element in intron 2 and three types of Alu elements in intron 4 and 9, with varying copies of minisatellites. Reconstruction of coding and noncoding sequence trees revealed concordances and discordances with regard to the branching of RHAG-like genes in higher primates. A joined tree of Rh50 glycoproteins and Rh30 polypeptides shows that the former evolved at a rate about two times slower than the latter. Statistical tests demonstrated that at least a portion of the RHAG gene was subjected to a positive selection during evolution of anthropoids.

Evolution of RH genes in hominoids: characterization of a gorilla RHCE-like gene.

The human RH locus is responsible for the expression of the Rh blood group antigens. It consists of two closely linked genes, RHD and RHCE, that exhibit 92% similarity between coding regions. These observations suggest that they are derived from a relatively recent duplication event. Previously a study of nonhuman primate RH-like genes demonstrated that ancestral RH gene duplication occurred in the common ancestor of man, chimpanzees and gorillas. By amplification of intron 3 and intron 4 of gorilla RH-like genes, we have now shown that, like man, gorillas possess two types of RH intron 3 (RHCE intron 3 being 289 bp longer than the RHD intron 3) and two types of intron 4 (RHCE intron 4 being 654 bp longer than the RHD intron 4). Here we report the characterization of a cDNA encoded by a gorilla RH-like gene which possesses introns 3 and 4 of the RHCE type. A comparison of this gorilla RHCE-like coding sequence with previously characterized human and ape cDNA sequences suggests that RH genes experienced complex recombination events after duplication in the common ancestor of humans, chimpanzees and gorillas.

Evolution of alpha 2-fucosyltransferase genes in primates: relation between an intronic Alu-Y element and red cell expression of ABH antigens.

Coding sequences of the paralogous FUT1 (H), FUT2 (Se), and Sec1 alpha 2-fucosyltransferase genes were obtained from different primate species. Analysis of the primate FUT1-like and FUT2-like sequences revealed the absence of the known human inactivating mutations giving rise to the h null alleles of FUT1 and the se null alleles of FUT2. Therefore, most primate FUT1-like and FUT2-like genes potentially code for functional enzymes. The Sec1-like gene encodes for a potentially functional alpha 2-fucosyltransferase enzyme in nonprimate mammals, New World monkeys, and Old World monkeys, but it has been inactivated by a nonsense mutation at codon 325 in the ancestor of humans and African apes (gorillas, chimpanzees). Human and gorilla Sec1's have, in addition, two deletions and one insertion, respectively, 5' of the nonsense mutation leading to proteins shorter than chimpanzee Sec1. Phylogenetic analysis of the available H, Se, and Sec1 mammalian protein sequences demonstrates the existence of three clusters which correspond to the three genes. This suggests that the differentiation of the three genes is rather old and predates the great mammalian radiation. The phylogenetic analysis also suggests that Sec1 has a higher evolutionary rate than FUT2 and FUT1. Finally, we show that an Alu-Y element was inserted in intron 1 of the FUT1 ancestor of humans and apes (chimpanzees, gorillas, orangutans, and gibbons); this Alu-Y element has not been found in monkeys or nonprimate mammals, which lack ABH antigens on red cells. A potential mechanism leading to the red cell expression of the H enzyme in primates, related to the insertion of this Alu-Y sequence, is proposed.

Rh gene evolution in primates: study of intron sequences.

By amplification and sequencing of RH gene intron 4 of various primates we demonstrate that an Alu-Sx-like element has been inserted in the RH gene of the common ancestor of humans, apes, Old World monkeys, and New World monkeys. The study of mouse and lemur intron 4 sequences allowed us to precisely define the insertion point of the Alu-Sx element in intron 4 of the RH gene ancestor common to Anthropoidea. Like humans, chimpanzees and gorillas possess two types of RH intron 4, characterized by the presence (human RHCE and ape RHCE-like genes) or absence (human RHD and ape RHD-like genes) of the Alu-Sx element. This led us to conclude that in the RH common ancestor of humans, chimpanzees, and gorillas, a duplication of the common ancestor gene gave rise to two genes, one differing from the other by a 654-bp deletion encompassing an Alu-Sx element. Moreover, most of chimpanzees and some gorillas posses two types of RHD-like intron 4. The introns 4 of type 1 have a length similar to that of human RHD intron 4, whereas introns 4 of type 2 display an insertion of 12 bp. The latest insertion was not found in the human genome (72 individuals tested). The study of RH intron 3 length polymorphism confirmed that, like humans, chimpanzees and gorillas possess two types of intron 3, with the RHD-type intron 3 being 289 bases shorter than the RHCE intron 3. By amplification and sequencing of regions encompassing introns 3 and 4, we demonstrated that chimpanzee and gorilla RH-like genes displayed associations of introns 3 and 4 distinct to those found in man. Altogether, the results demonstrate that, as in humans, chimpanzee and gorilla RH genes experienced intergenic exchanges.

Comparison of allele O sequences of the human and non-human primate ABO system.

Like humans, non-human primates express the antigens A and B of the ABO histoblood group system. In chimpanzees, only A and O types are found, while the types A, B, AB, and O are found in macaques. The sequences of exons 6 and 7 of two chimpanzee O alleles (Odel and O(x), two macaque species O alleles (rhesus monkey and crab-eating macaque), and sequences of exon 7 of two major chimpanzee A alleles (A1ch and A2ch) were established. The sequences of cDNAs corresponding to the chimpanzee and rhesus monkey O alleles were characterized from exon 1 to 7 and from exon 4 to 7, respectively. A comparison of our results with ABO gene sequences already published by others demonstrates that human and non-human primate O alleles are species-specific and result from independent silencing mutations. These observations reinforce the hypothesis that the maintenance of the ABO gene polymorphism in primates reflects convergent evolution more than transpecies inheritance of ancestor alleles.

Gorilla RH-like genes and antigens.

It has been previously shown that most of the human IgG monoclonal D-specific antibodies define a polymorphism in the gorilla consisting of two phenotypes: Dgor-positive and Dgor-negative. By quantitative indirect immunofluorescence assay and quantitative immunoblotting it was evaluated that the number of Dgor antigenic sites per gorilla red cell varies from a level equivalent to that observed for human RhD-positive cells to a level eight times higher. By immunoblotting with a rabbit reagent specific for the carboxylic end of human Rh-polypeptides it was demonstrated that RBCs from all gorillas, whatever their Dgor phenotype, possess 33000 relative molecular mass Rh-like polypeptides. The expression of the Dgor antigen was shown to be associated with the presence of three polymorphic bands defined by Southern blot using a human exon 4 RHCE probe, and to a length polymorphism of gorilla intron 3 evidenced by polymerase chain reaction. By contrast, the expression of the Dgor antigen was not associated to the length polymorphism of gorilla intron 4 which is related to the presence or absence of an Alu-Sx element in intron 4, paralleling the situation observed in human. These results confirmed the presence in the gorilla genome of at least two RH-like genes, one of which being responsible for Dgor polymorphism. The phylogenesis of the human and gorilla RH genes is discussed in light of the comparison of intron 4 sequences.

Use of LOR-15C9 monoclonal anti-D to differentiate erythrocytes with the partial DvI antigen from those with either partial D antigens or weak D antigens.

Historically, red blood cells (RBCs) with partial D antigens have been defined serologically by their pattern of reactivity with polyclonal and monoclonal anti-D. Although numerous variants have been described in tests with well-characterized monoclonal anti-D, definition remains difficult to ascertain serologically. RBCs of known partial D type were tested with LOR-15C9 (a monoclonal anti-D) and commercial anti-D by the tube indirect antiglobulin test (IAT), by micro typing system IgG gel cards, and by immunoblotting. By IAT, LOR-15C9 reacted strongly with DIIIa, DIIIc, DVa, DVI, DVII, and DFR RBCs in addition to RBCs with common D antigens; weakly with DII, DNU, and DIIIb RBCs; and not at all with DIVa, DIVb, DBT, or R0 Har RBCs. Reactivity was variable (1+ to 4+), with RBCs classified as weak D (Du). As expected, the commercial anti-D agglutinated all D variants and weak D RBC samples by the IAT and by using IgG gel cards; however, the reactivity with DVI RBCs was weaker than with LOR- 15C9. By immunoblotting, LOR-15C9 detected a band with an apparent molecular mass of approximate Mr 30,000-34,000 in membranes prepared from D-positive, DIIIa, DIIIc, DVa, DVI, DVII, and DFR RBCs and an additional band of Mr 20,000-22,000 in membranes prepared from DVI RBCs. No band(s) was detected in membranes from DII, DNU, DIIIb, DIVa, DIVb, DBT, R0 Har, weak D, or D-negative samples. LOR-15C9 provides a useful tool to identify positively DVI samples and thereby differentiate this partial D from other D variants and from weak D samples.

Evolution of fucosyltransferase genes in vertebrates.

Cloning and expression of chimpanzee FUT3, FUT5, and FUT6 genes confirmed the hypothesis that the gene duplications at the origin of the present human cluster of genes occurred between: (i) the great mammalian radiation 80 million years ago and (ii) the separation of man and chimpanzee 10 million years ago. The phylogeny of fucosyltransferase genes was completed by the addition of the FUT8 family of alpha(1,6)fucosyltransferase genes, which are the oldest genes of the fucosyltransferase family. By analysis of data banks, a new FUT8 alternative splice expressed in human retina was identified, which allowed mapping the human FUT8 gene to 14q23. The results suggest that the fucosyltransferase genes have evolved by successive duplications, followed by translocations, and divergent evolution from a single ancestral gene.

Polymerase chain reaction on cerebrospinal fluid cells in the detection of leptomeningeal involvement by B-cell lymphoma and leukaemia: a novel strategy and its implications.

In the search of B-cell lymphoma/leukaemia dissemination to cerebrospinal fluid (CSF), we used the highly sensitive semi-nested PCR (snPCR) for the analysis of IgH gene rearrangements. This method detects a rearranged IgH gene from a single B lymphocyte which may or may not represent the neoplastic B-cell population. We therefore performed multiple snPCR (three to five) experiments on the same CSF sample, postulating that the detection of a band of the same size and sequence in different PCR runs was highly indicative of a clonal population. 17 consecutive cases with a differential diagnosis of primary (PCNSL) (n=10) or secondary (SCNSL) (n=7) CNS lymphoma or leukaemia were investigated by the new strategy. The clonal nature of the B-cell population was confirmed in 3/10 of suspected PCNSL, and in six other cases the PCR study was indicative of reactive lymphocytosis. One case revealed a clonal B-cell population in the clinical context of an autoimmune disorder. Evidence of clonal B-cell population was found in 4/7 of suspected SCNSL. In one of these cases the detected band and its sequence proved identical to that of the primary nodal lymphoma. We believe that the evaluation of B-cell clonality in CSF requires multiple snPCR amplification on the same sample to compare the size of the products and, if necessary, the DNA sequences to ascertain the diagnosis of malignancy in equivocal cytologic and clinical findings.