Luis M. Allende

Immunodeficiency associated with anorexia nervosa is secondary and improves after refeeding

Several studies have addressed the question of starvation effects on immune function by means of changes in lymphocyte subsets, cytokine induction or lymphocyte activation. Anorexia nervosa (AN) patients are severely malnourished and contradictory results have been obtained regarding the accompanying immunodeficiency, including its assignation as a part of the primary nervous disorder. In the present work, an extensive immunological function examination was carried out on 40 AN patients who were compared with a control group of 14 healthy girls. The AN patients were also classified according to their nutritional status (by the Body Mass Index: BMI), this being critical for a better understanding of these secondary immunodeficiency bases. Moreover, another immune system study was performed on five patients after refeeding. Lymphocyte subsets and function, cytokine induction and peripheral blood concentrations, and innate as well as humoral immunity were evaluated. Deregulation in the cytokine network, owing to the interaction of the central nervous (CNS) and immune systems, seems to be the initial immune alteration in AN immunodeficiency but it has not been disproved that the immunodeficiency is a direct consequence of the original psychiatric perturbation. Spontaneous high levels of circulating interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) have been observed; this is probably one of the causes of the anomalies found in the T‐cell subpopulations (mainly the naive CD4+CD45RA+ reduction and the cytotoxic CD8+ increase) and T‐cell activation status (mainly the down‐regulation of the CD2 and CD69 activation pathways). This finally leads to an impairment, not only in T‐cell function but also in T‐cell to B‐cell co‐operation. The AN specificity of these results is confirmed by the fact that these immune alterations improve after refeeding and when nutritional status becomes less critical, which also suggests that AN immunodeficiency is indeed secondary to malnutrition.

A Point Mutation in a Domain of Gamma Interferon Receptor 1 Provokes Severe Immunodeficiency

ABSTRACT Gamma interferon (IFN-γ) and the cellular responses induced by it are essential for controlling mycobacterial infections. Most patients bearing an IFN-γ receptor ligand-binding chain (IFN-γR1) deficiency present gross mutations that truncate the protein and prevent its expression, giving rise to severe mycobacterial infections and, frequently, a fatal outcome. In this report a new mutation that affects the IFN-γR1 ligand-binding domain in a Spanish patient with mycobacterial disseminated infection and multifocal osteomyelitis is characterized. The mutation generates an amino acid change that does not abrogate protein expression on the cellular surface but that severely impairs responses after the binding of IFN-γ (CD64 and HLA class II induction and tumor necrosis factor alpha and interleukin-12 production). A patients younger brother, who was also probably homozygous for the mutation, died from meningitis due toMycobacterium bovis. These findings suggest that a point mutation may be fatal when it affects functionally important domains of the receptor and that the severity is not directly related to a lack of IFN-γ receptor expression. Future research on these nontruncating mutations will make it possible to develop new therapeutical alternatives in this group of patients.

The Old World sparrows (genus Passer) phylogeography and their relative abundance of nuclear mtDNA pseudogenes.

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).

Longitudinal analysis of immune function in the first 3 years of life in thymectomized neonates during cardiac surgery

The purpose of this study is to evaluate the effects of neonatal thymectomy in the functional capacity of the immune system. We selected a group of 23 subjects, who had undergone thymectomy in their first 30 days of life, during an intervention for congenital heart disease. Several parameters of the immune system were evaluated during their first 3 years of life. Lymphocyte populations and subpopulations (including naive, memory and effector subpopulations), T cell receptor (TCR) Vβ repertoire, response of T cells following in vitro stimulation by mitogen, quantification of immunoglobulins, TCR excision circles (TRECS) and interleukin (IL)‐7 were measured. We found that neonatal thymectomy produces long‐term diminution in total lymphocyte counts, especially in naive CD4+ and CD8+ T cells. Additionally, TRECS were decreased, and plasma IL‐7 levels increased. A statistically significant negative correlation was found between absolute CD4+ T cells and IL‐7 (r = −0·470, P = 0·02). The patients did not suffer more infectious events than healthy control children, but thymectomy in neonates resulted in a significant decrease in T lymphocyte levels and TRECS, consistent with cessation of thymopoiesis. This could produce a compromise in immune function later in life, especially if the patients suffer T cell depletion and need a reconstitution of immune function.

Phylogeography of crossbills, bullfinches, grosbeaks, and rosefinches

Abstract: 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.

HLA molecular markers in Tuvinians: a population with both Oriental and Caucasoid characteristics

HLA class I and class II alleles have been studied for the first time in the Turkish‐speaking Tuvinian population, which lives in Russia, North of Mongolia and close to the Altai mountains. Comparisons have been done with about 11000 chromosomes from other worldwide populations, and extended haplotypes, genetic distances, neighbor joining dendrograms and correspondence analyses have been calculated. Tuvinians show an admixture of Mongoloid and Caucasoid characters, the latter probably coming from the ancient Kyrgyz background or, less feasibly, more recent Russian Caucasoid admixture. However, Siberian population traits are not found and thus Tuvinians are closer to Central Asian populations. Siberians are more related to Na‐Dene and Eskimo American Indians; Amerindians (from nowadays Iberian–America) are not related to any other group, including Pacific Islanders, Siberians or other American Indians. The ‘more than one wave’ model for the peopling of the Americas is supported.

Differential Biological Role of CD3 Chains Revealed by Human Immunodeficiencies

The biological role in vivo of the homologous CD3γ and δ invariant chains within the human TCR/CD3 complex is a matter of debate, as murine models do not recapitulate human immunodeficiencies. We have characterized, in a Turkish family, two new patients with complete CD3γ deficiency and SCID symptoms and compared them with three CD3γ-deficient individuals belonging to two families from Turkey and Spain. All tested patients shared similar immunological features such as a partial TCR/CD3 expression defect, mild αβ and γδ T lymphocytopenia, poor in vitro proliferative responses to Ags and mitogens at diagnosis, and very low TCR rearrangement excision circles and CD45RA+ αβ T cells. However, intrafamilial and interfamilial clinical variability was observed in patients carrying the same CD3G mutations. Two reached the second or third decade in healthy conditions, whereas the other three showed lethal SCID features with enteropathy early in life. In contrast, all reported human complete CD3δ (or CD3ε) deficiencies are in infants with life-threatening SCID and very severe αβ and γδ T lymphocytopenia. Thus, the peripheral T lymphocyte pool was comparatively well preserved in human CD3γ deficiencies despite poor thymus output or clinical outcome. We propose a CD3δ ≫ CD3γ hierarchy for the relative impact of their absence on the signaling for T cell production in humans.

Kinetics of peripheral blood lymphocyte subpopulations predicts the occurrence of opportunistic infection after kidney transplantation

Serial monitoring of peripheral blood lymphocyte subpopulations (PBLSs) counts might be useful in predicting post‐transplant opportunistic infection (OI) after kidney transplantation (KT). PBLSs were prospectively measured in 304 KT recipients at baseline and post‐transplant months 1 and 6. Areas under receiver operating characteristic curves were used to evaluate the accuracy of different subpopulations in predicting the occurrence of overall OI and, specifically, cytomegalovirus (CMV) disease. We separately analyzed patients not receiving (n = 164) or receiving (n = 140) antithymocyte globulin (ATG) as induction therapy. In the non‐ATG group, a CD8+ T‐cell count at month 1 <0.100 × 103 cells/μl had negative predictive values of 0.84 and 0.86 for the subsequent occurrence of overall OI and CMV disease, respectively. In the multivariate Cox model, a CD8+ T‐cell count <0.100 × 103 cells/μl was an independent risk factor for OI (adjusted hazard ratio: 3.55; P‐value = 0.002). In the ATG group, a CD4+ T‐cell count at month 1 <0.050 × 103 cells/μl showed negative predictive values of 0.92 for the subsequent occurrence of overall OI and CMV disease. PBLSs monitoring effectively identify KT recipients at low risk of OI, providing an opportunity for individualizing post‐transplant prophylaxis practices.

A novel CD18 genomic deletion in a patient with severe leucocyte adhesion deficiency: a possible CD2/lymphocyte function‐associated antigen‐1 functional association in humans

Leucocyte adhesion deficiency (LAD) is an autosomal‐recessive genetic disease that is characterized clinically by severe bacterial infections and caused by mutations in the CD18 gene that codes for the β2 integrin subunit. A patient with a severe LAD phenotype was studied and the molecular basis of the disease was identified as a single homozygous defect in a Herpes virus saimiri (HVS)‐transformed T‐cell line. The defect identified involves a deletion of 171 bp in the cDNA that encodes part of the proteic extracellular domain. This genetic abnormality was further studied at the genomic DNA level and found to consist of a deletion of 169 bp (from − 37 of intron 4 to + 132 of exon 5), which abolishes the normal splicing and results in the total skipping of exon 5. The 171‐bp shortened ‘in‐frame’ mRNA not only resulted in the absence of CD18 expression on the cell surface but also in its absence in the cytoplasm of HVS T‐cell lines. Functionally, the LAD‐derived HVS T‐cell lines showed a severe, selective T‐cell activation impairment in the CD2 (but not in the CD3) pathway. This defect was not reversible when exogenous interleukin‐2 (IL‐2) was added, suggesting that there is also a functional interaction of the lymphocyte function‐associated antigen‐1 (LFA‐1) protein in the CD2 signal transduction pathway in human T cells, as has been previously reported in mice and in the human Papillon–Lefèvre syndrome. Thus, HVS transformation is not only a suitable model for T‐cell immunodeficiency studies and characterization, but is also a good system for investigating the immune system in pathological conditions. It may also be used in the future in cellular models for in vitro gene‐therapy trials.

Mutations of CD40 ligand in two patients with hyper-IgM syndrome

Two patients with the X-linked form of the hyper-IgM syndrome have been studied. Both patients present: 1. Mutations in the CD40L gene (a nonsense point mutation that introduces a termination codon at the extracellular domain of the protein, and a deletion that eliminates exon 4 as consequence of an abnormal splicing). 2. Lack of CD40L expression on the lymphocyte surface after stimulation with ionomycin and PMA. 3. Altered lymphocytic proliferation in response to anti-CD3. 4. Hyper IgM, low IgG and IgA levels and neutropenia. One of the patients shows, in addition, low Natural Killer cell numbers and severe herpetic infections, which distinguishes this case from the common hyper-IgM syndrome phenotype. Finally, a hyper-IgM stable phenotype has been immortalized by Herpes virus Saimiri for the first time.