VHL mosaicism can be detected by clinical next-generation sequencing and is not restricted to patients with a mild phenotype.

The identification of Von Hippel-Lindau (VHL) mosaic mutations by conventional Sanger sequencing requires a labour-intensive enrichment step, thus explaining that mosaicism occurrence is underestimated in patients. Nowadays, it is possible to detect mutation in cell sub-populations by next-generation sequencing (NGS). Here, we described a diagnosis strategy using NGS with high coverage in a series of eight patients who were negative for a VHL abnormality by Sanger sequencing and deletion search. In two patients, a mosaic mutation in VHL was detected by NGS. One patient with a 5.7% mutated allele frequency had a severe phenotype and an early disease onset. In conclusion, clinical NGS in an hospital molecular oncogenetics laboratory is an efficient tool to identify VHL mosaic mutation. Its use may improve patient monitoring and genetic counseling.

Comparative analysis of naïve and memory CD4+ and CD8+ T-cell subsets in bone marrow and G-CSF-mobilized peripheral blood stem cell allografts: impact of donor characteristics.

OBJECTIVE: Donor T cells expressing lymph node homing receptors are the foremost initiators of acute graft-vs-host disease (aGVHD), and a high proportion of CD4(+)CCR7(+) T cells in human leukocyte antigen-matched allografts has been shown to confer a high risk of aGVHD without interfering in other outcomes. METHODS: Naïve, central memory (T(CM)), effector memory (T(EM)), and terminally differentiated effector memory (T(TD)) subsets, further subdivided by CD28 expression, were compared in 52 bone marrow and 37 granulocyte colony-stimulating factor-mobilized peripheral blood harvests. RESULTS: CCR7(+) cells (naïve and T(CM)) predominated in the CD4(+) population, whereas CD8(+) memory cells were chiefly CCR7(neg) in the grafts. Donor age, antecedent of chronic infections, and graft type were independent factors influencing graft composition. CD8(+) naïve cells negatively correlated and CD8(+) T(EM) positively correlated with age. Cytomegalovirus seropositivity was associated with more CD8(+) T(TD) and diminished CD28 expression. Toxoplasmosis seropositivity was associated with more CD4(+) T(CM) (p = 0.021). Marrow grafts comprised more CD28(+) cells within CD8(+) T(TD), but the percentage of CD4(+)CCR7(+) cells did not differ significantly between the two graft sources. Each of the four CD4(+) subsets and the percentage of CD4(+)CCR7(+) cells (p < 0.001) were correlated between graft and venous blood analyzed in 42 donors before harvest procedures. CONCLUSION: This study provides reference values for CD4(+) and CD8(+) naïve and memory subsets within allografts applicable to the healthy donor population and indicates that beforehand analysis of a whole-blood sample can help evaluating the risk of aGVHD conferred by each donor and, when possible, choosing the one conferring the lowest risk.

Highly focused clonal composition of CD8(+) CD28(neg) T cells in aqueous humor of fuchs heterochromic cyclitis.

Fuchs heterochromic cyclitis (FHC) is characterized by a predominant CD8(+) T cell subset infiltrating the anterior chamber, but the clonal composition of these T cells is unknown. In the present study, T cell repertoire diversity of the accumulating T cells was analyzed to investigate if a high degree of restriction could indicate antigen-driven immune response. Aqueous humor (AH) and peripheral blood cells were collected in two patients with FHC. T cell repertoire diversity was screened by T cell receptor (TCR) BV family expression. In one patient, several BV gene segments were used by lymphocytes from the AH but with over-representation of BV16 that accounted for around half of the expressed intraocular repertoire. In the other patient, a more restricted TCRBV usage was found in AH, as only BV15 and BV18 were expressed in the ocular sample. In this patient, virtually all AH CD8(-) T-cells were CD28- and CD57-negative by three-color flow cytometry, an immunophenotype suggestive of past antigenic stimulation. High resolution immunoscope analysis of TCRBV CDR3 profiles and sequencing of subcloned TCRBV-BJ PCR products evidenced a highly restricted TCRBV-BJ usage, since virtually all the intraocular cells comprise only five clonotypes in this patient. Unique peaks of CDR3 length were found in BV15 joined to BJ2S1, BJ2S3 and especially BJ2S5, in AH but did not predominate in blood. Conversely, identical clonotypes using rearranged BV18 and BJ2S7 gene segments were detected in both AH and peripheral blood. Maintenance of the TCRBV18-BJ2S7 clonotypes in aqueous humor was demonstrated over 6 months in this patient, with a switch in the predominance of two clonotypes. Our results show the presence of a finite number of CD8(+)CD28(neg) T cell clonotypes, which suggests an antigen-driven process and the involvement of these T cells in the pathogenesis of FHC.