Phenotype markers and cytokine intracellular production by CD8+ gammadelta T lymphocytes do not support a regulatory T profile in Behçet's disease patients and healthy controls.

gammadelta T lymphocytes (GD) have been suggested as one of the causes of cytokine dysregulation that results in neutrophils hyperactivation in Behçet's disease (BD) patients. In addition, GD can provoke cytotoxic lesions in autoimmune diseases by interaction with MICA (MHC class I chain-related A) molecules, through NKG2D receptor on its surface. In contrast, the CD8+ subset of gammadelta T lymphocytes (GDCD8+) has been related to regulatory T activity. The aim of this study was to determine the phenotype and the intracellular cytokine profile in GD from peripheral blood, to discern if they were skewed to an effector or regulatory pattern in BD. We performed phenotype analysis, by three-colour flow cytometry, in 28 BD, 15 healthy controls (HC) and 14 patients with recurrent bucal ulcers (RBU). We studied intracellular cytokine production in 10 BD and 14 HC, after polyclonal stimulation. In addition, we analysed serum IL-15 and soluble MICA, by ELISA, in 27 BD, 21 HC and 40 rheumatoid arthritis patients. The hallmark in BD was a specific increase in CD8 expression by GD, and in GDCD8+ absolute numbers. Most of GDCD8+ presented CD8 alphaalpha homodimers and were negative for CD103, Foxp3 and CTLA-4. GDCD8+ and GDCD8- were high IFNgamma-, but poor IL-2, IL-10, TGFbeta and IL-4-producing cells, with no differences between BD and HC. NKG2D expression on CD8+ T cells, serum IL-15 and soluble MICA were not significantly increased in BD. Our results do not suggest a T regulatory profile for GDCD8+ neither in HC, nor in BD. We cannot rule out other suppression mechanisms or some heterogeneity within this subset that could contribute to regulatory function.

MICA-HLA-B haplotype diversity and linkage disequilibrium in a population of Jewish descent from Majorca (the Balearic Islands).

The major histocompatibility complex class I chain-related A (MICA) gene is located 46 kb centromeric of human leukocyte antigen (HLA)-B and is highly polymorphic, similar to HLA genes. This allelic variation may influence the affinity of MICA molecules to their receptor on natural killer, gammadelta T and CD8+ T cells, NKG2D, and the immune response to organ transplantation and disease susceptibility. In the present study, we typed MICA and HLA-B polymorphisms in 95 individuals from a population of Jewish descent (Chuetas) and 195 individuals of Caucasian origin from Majorca (the Balearic Islands). MICA*008, -*004, and -*002 were the most common alleles and accounted for 53 and 60% in Chuetas and Majorcans, respectively. Other common alleles (frequency >5%) were MICA*016, -*009, -*012, -*007, and -*017 in Chuetas and -*009, -*001, and -*018 in Majorcans. We also studied two-locus haplotype diversity and linkage disequilibrium (LD). Both populations presented haplotypes with significant LD that were shared by other Caucasians populations, but we reported particular haplotypes in the Chueta group: MICA*002-HLA-B*38, MICA*016-HLA-B*35, MICA*012-HLA-B*55, and MICA*017-HLA-B*57. These haplotypes were not reported in other studies at high frequencies. In conclusion, the Chueta population presents a particular genetic pool but has affinities with the host population.

A new mutation in exon 7 of NEMO gene: late skewed X-chromosome inactivation in an incontinentia pigmenti female patient with immunodeficiency.

Incontinentia pigmenti is an X-linked genodermatosis, lethal in males. Affected females survive because of X-chromosome dizygosity and negative selection of cells carrying the mutant X-chromosome, and for this reason the skewed X inactivation pattern is often used to confirm the diagnosis. The most frequent mutation is a deletion of part of the NEMO gene (NEMODelta4-10), although other mutations have been reported. Mutations of NEMO which do not abolish NF-kappaB activity totally permit male survival, causing an allelic variant of IP called hypohidrotic ectodermal dysplasia and immunodeficiency (HED-ID). We present a non-classical IP female patient who also suffered transient immunodeficiency because of a late and progressive selection against peripheral blood cells carrying an active mutated X-chromosome. This finding suggests that in the absence of known mutation the X-inactivation studies used in genetic counselling can induce mistakes with some female patients. At the age of 3 years and 6 months, all immunodeficiency signs disappeared, and the X-chromosome inactivation pattern was completely skewed. The low T cell proliferation and CD40L expression corroborate the important role of NEMO/ NF-kappaB pathway in T cell homeostasis. The decreased NEMO protein amount and the impaired IkBalpha degradation suggest that this new mutation, NM_003639: c.1049dupA, causes RNA or protein instability. To our knowledge, this is the first time that selection against the mutated X-chromosome in X-linked disease has been documented in vivo.

Skewed inhibitory receptors expression in a TAP2-deficient patient.

Most of patients suffering from HLA class I deficiency due to mutations in TAP genes show a significative increase of the peripheral minor Vdelta1+ subpopulation of gammadelta T cells. Surface expression of inhibitory receptors (IR) for HLA class I molecules have been mainly attributed to Vdelta2+ gammadelta T clones. In this study we have analysed the expression of these receptors in both subsets of gammadelta T peripheral lymphocytes. We studied 16 healthy controls and a reported case of homozygous TAP2 mutation with a marked increase of Vdelta1+ gammadelta T cells. MICA/B presence in monocytes was also evaluated. In healthy subjects, the expression of CD94 and CD94/NKG2A was higher in the Vdelta2+ subset but cells bearing the IR ILT2 were found increased in the Vdelta1+. The patient Vdelta2+ gammadelta T cells showed the same IR expression than normal controls, in contrast the Vdelta1+ subset presented a special pattern of very high expression of CD94 and ILT2 and low of CD94/NKG2A. The presence of a new IR poorly represented in healthy individuals could account for the selective increase of Vdelta1+ gammadelta T in TAP-deficient patients. MICA/B surface expression in monocytes was not shifted in our patient.