[The Role of Extracellular Calcium Ions Reduction in T Cell Activation in Human Peripheral Blood].

Calcium plays a fundamental role in many essential live functions. It is well-known that many infections can lead to hypocalcaemia in humans. The importance of extracellular calcium concentration ([Ca2+]o) in T-cell activation is well recognized, but [Ca2+]o levels necessary for lymphocyte activation have not been investigated in detail. Whole blood from healthy donors was stimulated by immobilized anti-CD3 plus soluble co-stimulation anti-CD28 mAb and activation parameters have been analyzed. Interleukins-2 (IL-2), JL-4, IL-17A, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) production and CD4+CD69+, CD4+CD25+, CD4+(CYTOKINE)+ T cells were used as activation parameters. To change current [Ca2+]o values in PB we used EGTA. No EGTA influence on resting T cells was shown. Dependences of T-cell activation parameters on various [Ca2+]o were studied. These data indicate that extracellular Ca2+ chelation by EGTA leads to non-linear dependences of T-cell activation parameters on [Ca2+]o values. Obtained dependence of the number of CD4+CD69+ T cells from EGTA can be represented as a nonlinear curve with two distinct peaks. Cytokines production by activated Th1, Th2 and Th17 cells and CD4+(CYTOKINE)+ T cells have been analyzed in dependence on EGTA. The first peak is close to the norm-pathology border. The second peak is in the pathological [Ca2+]o values of PB. However, the local minimum between them is entirely in the "pathological" range. Obtained dependences can be represented as a nonlinear curve with two distinct peaks. All dependences shape have similar curve describing the influence of [EGTA] values on activated CD4+CD69+ T cells. Physiological significance of obtained data discussed.

A new variant of Charcot-Marie-Tooth disease type 2 is probably the result of a mutation in the neurofilament-light gene.

Charcot-Marie-Tooth (CMT) disease is the most common inherited motor and sensory neuropathy. The axonal form of the disease is designated as "CMT type 2" (CMT2). Although four loci known to be implicated in autosomal dominant CMT2 have been mapped thus far (on 1p35-p36, 3q13. 1, 3q13-q22, and 7p14), no one causative gene is yet known. A large Russian family with CMT2 was found in the Mordovian Republic (Russia). Affected members had the typical CMT2 phenotype. Additionally, several patients suffered from hyperkeratosis, although the association, if any, between the two disorders is not clear. Linkage with the CMT loci already known (CMT1A, CMT1B, CMT2A, CMT2B, CMT2D, and a number of other CMT-related loci) was excluded. Genomewide screening pinpointed the disease locus in this family to chromosome 8p21, within a 16-cM interval between markers D8S136 and D8S1769. A maximum two-point LOD score of 5.93 was yielded by a microsatellite from the 5' region of the neurofilament-light gene (NF-L). Neurofilament proteins play an important role in axonal structure and are implicated in several neuronal disorders. Screening of affected family members for mutations in the NF-L gene and in the tightly linked neurofilament-medium gene (NF-M) revealed the only DNA alteration linked with the disease: a A998C transversion in the first exon of NF-L, which converts a conserved Gln333 amino acid to proline. This alteration was not found in 180 normal chromosomes. Twenty unrelated CMT2 patients, as well as 26 others with an undetermined form of CMT, also were screened for mutations in NF-L, but no additional mutations were found. It is suggested that Gln333Pro represents a rare disease-causing mutation, which results in the CMT2 phenotype.

Screening for mutations in the peripheral myelin genes PMP22, MPZ and Cx32 (GJB1) in Russian Charcot-Marie-Tooth neuropathy patients.

Charcot-Marie-Tooth disease (CMT) and related inherited peripheral neuropathies, including Dejerine-Sottas syndrome, congenital hypomyelination, and hereditary neuropathy with liability to pressure palsies (HNPP), are caused by mutations in three myelin genes: PMP22, MPZ and Cx32 (GJB1). The most common mutations are the 1.5 Mb CMT1A tandem duplication on chromosome 17p11.2-p12 in CMT1 patients and the reciprocal 1.5 Mb deletion in HNPP patients. We performed a mutation screening in 174 unrelated CMT patients and three HNPP families of Russian origin. The unrelated CMT patients included 108 clinically and electrophysiologically diagnosed CMT1 cases, 32 CMT2 cases, and 34 cases with unspecified CMT. Fifty-nine CMT1A duplications were found, of which 58 belonged to the CMT1 patient group. We found twelve distinct mutations in Cx32, six mutations in MPZ, and two mutations in PMP22. Of these respectively, eight, five, and two lead to a CMT1 phenotype. Eight mutations (Cx32: Ile20Asn/Gly21Ser, Met34Lys, Leu90Val, and Phe193Leu; MPZ: Asp134Gly, Lys138Asn, and Thr139Asn; PMP22: ValSer25-26del) were not reported previously. Phenotype-genotype correlations were based on nerve conduction velocity studies and mutation type.