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Autoimmune lymphoproliferative syndrome (ALPS) is characterized by lymphoproliferation and autoimmune clinical manifestations and is generally caused by defective Fas-mediated apoptosis. This report describes the first homozygous FASL gene mutation in a woman with clinical and immunologic features of ALPS. T-cell blasts from the patient did not induce FasL-mediated apoptosis on Fas-transfected murine L1210 or on Jurkat cells, and activation-induced cell death was impaired. Furthermore, Fas-dependent cytotoxicity was drastically reduced in COS cells transfected with the mutant FasL. In addition, FasL expression on T-cell blasts from the patient was similar to that observed in a healthy control, despite its bearing the high-producer genotype -844C/C in the FASL promoter. Sequencing of the patient's FASL gene revealed a new mutation in exon 4 (A247E). The location of A247E in the FasL extracellular domain and the conservation of the protein sequence of that region recorded in 8 species different from humans support the essential role of FasL COOH terminal domain in Fas/FasL binding. These findings provide evidence that inherited nonlethal FASL abnormalities cause an uncommon apoptosis defect producing lymphoproliferative disease, and they highlight the need for a review of the current ALPS classification to include a new ALPS type Ic subgroup., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

The BH3-only protein Bim is required for maintaining the homeostasis of the immune system, since Bim regulates the down-modulation of T-cell responses, mainly through cytokine deprivation. Using T-cell blasts from healthy donors and also from patients with autoimmune lymphoproliferative syndromes (ALPSs) due to homozygous loss-of-function mutation of FasL (ALPS-Ic) or heterozygous mutation in the Fas/CD95 death domain (ALPS-Ia), it is shown that the induction of Bim expression during the process of human T-cell blast generation is strictly dependent on FasL/Fas-mediated signaling. The main pathway by which Fas signaling regulates the levels of Bim expression in human T-cell blasts is the death-domain- and caspase-independent generation of discrete levels of H2O2, which results in the net increase of Foxo3a levels. The present results connect the 2 main pathways described until the moment for the control of T-cell responses: death receptor-mediated activation-induced cell death and apoptosis by cytokine deprivation., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Papillon-Lefèvre syndrome (PLS) is an inherited human disorder characterised by premature destruction of the periodontium of the deciduous and permanent teeth, palmoplantar hyperkeratosis, and increased susceptibility to bacterial infections during the first years of life. In this paper two PLS families have been studied. Family 1 presents a novel homozygous mutation (880T>C) in exon 6 causing Y294H amino acid substitution. Family 2 shows a previously described non-sense homozygous punctual change (72C>A) that introduces a termination codon at the extracellular domain of the protein (C24X)., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Papillon-Lefèvre syndrome (PLS) has recently been shown to be caused by mutations in the cathepsin C gene resulting in periodontal disease and palmoplantar keratosis. Thirteen different homozygous mutations have been characterised in PLS patients of different ethnic origin. In the present paper, a PLS patient is described who carries two novel mutations (706G>T and 872G>A) in the paternal and maternal chromosomes, respectively. This is the first compound patient described so far. In addition, a novel symptomless mutation (458C>T) in the cathepsin C gene is described in three homozygous individuals. Thus, not all mutations should be considered as a cause of disease, whether case studies or general population screening is performed. Another already described mutation that provoked the Haim-Munk syndrome (HMS) in Indian Jews has also been found to give rise to PLS in a Spanish family from Madrid. On the other hand, PLS patients are ameliorated by retinoids, which indicates that retinoids may be used as therapeutic agents in this immune system deficiency., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Summary: Three ataxia telangiectasia (AT) patients have been characterized immunologically and molecularly. Patient 1 presents two nondescribed splicing mutations which affect exons 15 and 21 of the ATM gene. The maternal defect consists of a G>A transition in the first nucleotide of the intron 21 donor splicing site which results in a complete deletion of exon 21. The paternal mutation consists of an A > C transversion in the intron 14 acceptor splicing site which produces a partial skipping of exon 15. Two abnormal alternative transcripts were found, respectively, 17 and 41 nucleotides shorter. Patient 2 presents a homozygous genomic deletion of 28 nucleotides in the last exon of the gene. This deletion changes the normal reading frame after residue 3003 of the protein and introduces a premature stop codon at residue 3008 that could originate a truncated ATM protein. Patient 3, a compound heterozygote, presents a defect which consists of a G > A transition in the first nucleotide of intron 62 donor splicing site which results in a complete deletion of exon 62. The results obtained during a three year period in the proliferation assays show an impaired PMA (phorbol myristate acetate) activation in specific T lymphocyte activation pathways (CD69, CD26, CD28, CD3, PHA, PWM and Con A mediated) but not in others (CD2, ionomycin, and Ig surface receptor). The possible link among specific ATM mutations and abnormal immune responses is unknown., Ministerio de Educación y Ciencia, Comunidad Autónoma de Madrid, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

The HLA profile of the Azoreans has been compared with those of other world populations in order to provide additional information regarding the history of their origins. The allele frequencies, genetic distances between populations, correspondence analyses and most frequent haplotypes were calculated. Our results indicate that the Azorean population most likely contains an admixture of high‐frequency Caucasoid, Mongoloid and, to a lesser degree, Negroid HLA genes. The middle Atlantic Azores Archipelago was officially colonized by the Portuguese after 1439 and historical records are concordant with the existence of Caucasoid and Negroid population. However, Mongoloid genes were not suspected, but the Oriental HLA haplotypes A24‐B44‐DR6‐DQ1, A29‐B21‐DR7‐DQ2 and A2‐B50‐DR7‐DQ2 are the fourth, fifth and sixth most frequent ones in Azores. A correspondence analysis shows that the Azorean population is equidistant from Asian and European populations and genetic distances are in some cases closer to the Asian than to European ethnic groups, and never are significantly different; also, B*2707 subtype is found in Asians and Azoreans (but not in Europeans) and the same Machado‐Joseph Disease founder haplotypes (Chr 14) are found in both Japanese and Azoreans. It is proposed that a Mongoloid population exists in Azores; whether, the arrival occurred prior to discovery is undetermined., Comunidad Europea, Ministerio de Educación, Comunidad Autónoma de Madrid, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Mitochondrial cytochrome b (cyt b) from 24 Carduelini species including crossbills, bullfinches, grosbeaks, rosefinches, and other related, but not conclusively classified species, was sequenced. These sequences were also compared with all the available sequences from the genera Carduelis, Serinus, and Passer. Phylogenetic analyses consistently gave the same groups of finches and the calculated divergence times suggest that speciation of the studied species occurred between 14 and 3 million years ago (Miocene-Pliocene), appearing before the Passer, Carduelis, and Serinus genera. Pleistocene glaciations may have been important in subspeciation. Crossbills are integrated within the genus Carduelis, and within redpolls; the common crossbill shows subspeciation with Loxia japonica in the Pleistocene epoch. Pinicola enucleator groups together with bullfinches and is probably the ancestor of the group. Hawfinch is only distantly related to the studied groups, and might either represent an isolated genus or be related to the New World genus Hesperiphona. The grosbeak genera Eophona and Mycerobas are clearly sister groups, and species belonging to the former might have given rise to Mycerobas species. The isolated (in classification) Uragus sibiricus and Haematospiza sipahi are included within the genus Carpodacus (rosefinches); Carpodacus nipalensis is outside the genus Carpodacus in the molecular analyses and might be an isolated species or related to the genus Montifringilla., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

A Papillon-Lefèvre patient with characteristic chronic periodontal disease and palmoplantar keratoderma was studied over a 4-year period. An abnormal T-cell phenotype was steadily observed in peripheral blood; both low numbers of CD29+ and CD45RO+ cells and a low density surface expression of CD2 and LFA-1 molecules were found. T-cell activation through CD3, CD2 and ConA, PWM and IL-2 receptors was normal; however, there was impairment in the activation via CD28. CD2, LFA-1 and CD45 molecules were normal in charge and molecular weight. There was no tissue sequestering of T lymphocytes in periodontal lesions, but rather a relative T-cell reduction. It is suggested that an important decrease of the so-called "memory/hyperreactive" (CD45RO-positive) T cells does exist; therefore, hyperreactive T cells would not be available in sufficient numbers to leave the bloodstream through blood vessel endothelium, and the periodontium would be left without these important defenses and thus exposed to chronic infections. A disregulated factor affecting the transition from "naive" to "memory" T cells and the increase in certain surface molecules expression (i.e., CD2, LFA-1, CD29, and CD45RO) or the reversion from memory to naive T cells may be responsible for the disease pathogenesis. CD2 and LFA-1 molecule synthesis might be conjointly regulated on T lymphocytes., Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Eleven new C4d genomic primate sequences of the fourth complement factor (C4) have been obtained. Seven of them belong to five species not yet explored for this gene: Pan paniscus (pygmy chimpanzee), Cercopithecus aethiops (green monkey), Macaca mulatta (rhesus monkey), Macaca fascicularis (cynomolgus), and Saguinus oedipus (cotton top tamarin). The New World monkeys (tamarins, four individuals) sequenced for C4 have a single C4d sequence only, which shows a B isotypic specificity and a Rodgers 3 (Rg3), Chido 1 (Ch1) antigenicity. Rg3 and Ch1 could thus be the oldest Rg/Ch specificity (at least 50 million years old) and Rg1, Rg2, Ch3, and Ch6 could be more recent human-specific antigens. Mechanisms of C4d polymorphism generation were analyzed by compiling all the presently available sequences. Examples of both point mutations and crossing-over events among C4d primate sequences could be detected. The problem of a possible trans-species inheritance of C4d polymorphism was addressed and two apparently contradicting dendrograms were obtained. One of them, constructed by using both exon and intron sequences, does not support trans-species evolution, but supports the proposed theory of extensive homogenization of the C4 genes occurring within each species, because alleles from each primate species cluster together. Another completely different dendrogram, obtained by using exon sequences only, suggests the existence of trans-species evolution for C4d polymorphism, because alleles belonging to different species cluster together in a way similar to that found for HLA class I or II alleles. However, orangutan sequences group together in both kinds of C4d sequence dendrograms and seem to have arisen from an ancestor different from that of chimpanzee, gorilla and man C4d sequences. Finally, further data have been obtained that support trans-species conservation of A-ness and B-ness and the existence of trans-specifically conserved allelic motifs, both in intronic and exonic s, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

The phylogenetic relationships of genus Passer (Old World sparrows) have been studied with species covering their complete world living range. Mitochondrial (mt) cyt b genes and pseudogenes have been analyzed, the latter being strikingly abundant in genus Passer compared with other studied songbirds. The significance of these Passer pseudogenes is presently unclear. The mechanisms by which mt cyt b genes become pseudogenes after nuclear translocation are discussed together with their mode of evolution, i.e., transition/transversion mitochondrial ratio is decreased in the nucleus, as is the constraint for variability at the three codon positions. However, the skewed base composition according to codon position (in 1st position the percentage is very similar for the four bases, in 2nd position there are fewer percentage of A and G and more percentage of T, and in 3rd codon position fewer percentage of G and T and is very rich in A and C) is maintained in the translocated nuclear pseudogenes. Different nuclear internal mechanisms and/or selective pressures must exist for explaining this nuclear/mitochondrial differential DNA base evolutive variability. Also, the phylogenetic usefulness of pseudogenes for defining relationships between closely related lineages is stressed. The analyses suggest that the primitive genus Passer species comes from Africa, the Cape sparrow being the oldest: P. hispaniolensis italiae is more likely conspecific to P. domesticus than to P. hispaniolensis. Also, Passer species are not included within weavers or Estrildinae or Emberizinae, as previously suggested. European and American Emberizinae sparrows are closely related to each other and seem to be the earliest species that radiated among the studied songbirds (all in the Miocene Epoch)., Ministerio de Educación, Comunidad de Madrid, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

The Fas-FasL pathway plays an important role in the homeostasis of mature lymphocytes, with defects causing autoimmune lymphoproliferative syndromes (ALPS). Human T-cell blasts are not sensitive to FasL or Apo2L/TRAIL-induced apoptosis unless they get reactivated, but either of those ligands inhibits their growth in the absence of cell death induction due to a cell cycle arrest in S-G2/M. In the present work, we have studied the mechanism(s) by which FasL or Apo2L/TRAIL regulate T-cell blast cell cycle in healthy donors and in two types of ALPS patients. Our data indicate that in human CD8+ T-cell blasts, Fas ligation, and especially Apo2L/TRAIL induce the p53-dependent decrease in cyclin-B1 levels. However, the induction of the negative cell cycle regulator p21WAF1 by FasL or Apo2L/TRAIL in either CD4+ or CD8+ T-cell blasts seems to be the main regulatory mechanism. This mechanism is dependent on caspase activation and on H2O2 generation. The increase in p21 levels by FasL or Apo2L/TRAIL is concomitant with p53 increases only in CD8+ T-cell blasts, with p21 levels maintained high for longer times than p53 levels. In CD4+ T-cell blasts p21 levels are controlled through a transient and p53-independent mechanism. The present results suggest that the etiology of ALP syndromes could be related not only to defects in apoptosis induction, but also in cell cycle regulation., Ministerio de Educación y Ciencia, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Cernunnos/XLF deficiency is a rare primary immunodeficiency classified within the DNA repair defects. Patients present with severe growth retardation, microcephaly, lymphopenia and increased cellular sensitivity to ionizing radiation. Here, we describe two unrelated cases with the same non-sense mutation in the NHEJ1 gene showing significant differences in clinical presentation and immunological profile but a similar DNA repair defect., FIS (Fondo de Investigación Sanitaria), MINECO (Ministerio de Economía y competitividad), CAM (Comunidad Autónoma de Madrid), Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

The Th1/Th2 balance plays a crucial role in the progression of different pathologies and is a determining factor in the evolution of infectious diseases. This work has aimed to evaluate the early, or on diagnosis, T-cell compartment response, T-helper subsets and anti-SARS-CoV-2 antibody specificity in COVID-19 patients and to classify them according to evolution based on infection severity. A unicenter, randomized group of 146 COVID-19 patients was divided into four groups in accordance with the most critical events during the course of disease. The immunophenotype and T-helper subsets were analyzed by flow cytometry. Asymptomatic SARS-CoV-2 infected individuals showed a potent and robust Th1 immunity, with a lower Th17 and less activated T-cells at the time of sample acquisition compared not only with symptomatic patients, but also with healthy controls. Conversely, severe COVID-19 patients presented with Th17-skewed immunity, fewer Th1 responses and more activated T-cells. The multivariate analysis of the immunological and inflammatory parameters, together with the comorbidities, showed that the Th1 response was an independent protective factor for the prevention of hospitalization (OR 0.17, 95% CI 0.03–0.81), with an AUC of 0.844. Likewise, the Th1 response was found to be an independent protective factor for severe forms of the disease (OR 0.09, 95% CI: 0.01–0.63, p = 0.015, AUC: 0.873). In conclusion, a predominant Th1 immune response in the acute phase of the SARS-CoV-2 infection could be used as a tool to identify patients who might have a good disease evolution., Instituto de Salud Carlos III (ISCIII) / FEDER, Fundación Mutua Madrileña, Depto. de Inmunología, Oftalmología y ORL, Depto. de Medicina, Fac. de Medicina, TRUE, pub

Human T cell receptor (TCR) immunodeficiencies (TCRID) are rare autosomal recessive disorders caused by mutations affecting TCR, CD3, or CD247 chains, which share developmental, functional, and TCR expression defects (1). Their rapid diagnosis is fundamental for patient survival and early hematopoietic stemcell transplantation.Here,we propose that studying gd T cells, which are often neglected, can be helpful for a timely diagnosis. We thus offer a diagnostic flowchart and some lab tricks based on published cases., Ministerio de Economia y Competitividad (MINECO), Insituto de Salud Carlos III (ISCIII), Comunidad de Madrid, Fundación Lair, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

El término retinoide engloba un grupo de compuestos que incluye el ácido retinoico (AR), el retinol (vitamina A) y una serie de derivados naturales y sintéticos que presentan actividad tipo vitamina A. En los últimos años, se ha comprobado que los retinoides en general ejercen funciones muy importantes en la regulación, diferenciación y homeostasis del desarrollo de vertebrados; además, estas moléculas están también implicadas en el desarrollo y maduración de gran variedad de tipos celulares (incluidas las del sistema inmune), así como en el tratamiento de diversas patologías como cáncer, leucemia, enfermedades cardiovasculares e inmunodeficiencias. En este trabajo se ha comprobado como las células mononucleares de sangre periférica estimuladas con anticuerpos anti-CD3 y retinol presentan una mayor proliferación linfocitaria que las que solamente han sido estimuladas con anti-CD3. El incremento de la proliferación linfocitaria es específicamente mediado vía receptor de la célula T (complejo TCR/CD3) y además provoca la regulación positiva de ciertas moléculas de adhesión/activación de la célula T: CD18, CD45R0 y CD25; también las citoquinas tipo Th1 (interleuquina-2 e interferon gamma) se encuentran positivamente reguladas tras la estimulación con el retinol. Por último, se ha estudiado el efecto del retinol sobre los linfocitos T activados de diferentes inmunodeficiencias encontrándose que sólo aquellos casos en que la vía de activación del CD3 se encuentra intacta, el efecto del retinol persite. Estos hallazgos permiten plantear su uso terapéutico en determinadas inmunodeficiencias

El término retinoide engloba un grupo de compuestos que incluye el ácido retinoico (AR), el retinol (vitamina A) y una serie de derivados naturales y sintéticos que presentan actividad tipo vitamina A. En los últimos años, se ha comprobado que los retinoides en general ejercen funciones muy importantes en la regulación, diferenciación y homeostasis del desarrollo de vertebrados; además, estas moléculas están también implicadas en el desarrollo y maduración de gran variedad de tipos celulares (incluidas las del sistema inmune), así como en el tratamiento de diversas patologías como cáncer, leucemia, enfermedades cardiovasculares e inmunodeficiencias. En este trabajo se ha comprobado como las células mononucleares de sangre periférica estimuladas con anticuerpos anti-CD3 y retinol presentan una mayor proliferación linfocitaria que las que solamente han sido estimuladas con anti-CD3. El incremento de la proliferación linfocitaria es específicamente mediado vía receptor de la célula T (complejo TCR/CD3) y además provoca la regulación positiva de ciertas moléculas de adhesión/activación de la célula T: CD18, CD45R0 y CD25; también las citoquinas tipo Th1 (interleuquina-2 e interferon gamma) se encuentran positivamente reguladas tras la estimulación con el retinol. Por último, se ha estudiado el efecto del retinol sobre los linfocitos T activados de diferentes inmunodeficiencias encontrándose que sólo aquellos casos en que la vía de activación del CD3 se encuentra intacta, el efecto del retinol persite. Estos hallazgos permiten plantear su uso terapéutico en determinadas inmunodeficiencias