Discrimination of T-cell subsets and T-cell receptor repertoire distribution.

Flow cytometry-based analysis of T-cell receptor (TCR) repertoires is an essential tool for the detection of clonal T-cell expansions in physiologic and pathologic conditions. Individual T-cell subsets can be investigated based on their surface properties. The aims of our study were to provide reference values for various disease settings and delineate the contribution of individual TCR repertoires to the human T-cell differentiation pathway. We analyzed blood of 66 healthy subjects aged 0 (cord blood) to 72 years. Lymphocyte subpopulations and TCR repertoires were simultaneously explored using antibodies specific to CD3, CD4, CD8, CD45RA, CCR7, CD27, CD57 and a set of 25 antibodies detecting human TCR-Vß chains. Statistical analysis included Wilcoxon, paired t and ANOVA tests. Initially, TCR expansion values were calculated based on the analysis of TCR-Vß distribution on CD4+ and CD8+ T cells. We then established gating strategies and an algorithm for data analysis allowing for discrimination of T-cell subsets and TCR distribution. Dominant TCR expansions were present within effector as opposed to central/effector memory or naive cells, e.g., median TCR-Vß expansion rate was highest on CD45RA+/CCR7- effector CD4+/8+ cells (eight and 11-fold, respectively). Remarkably, TCR expansions were missing (0) or very low (0.5) on CD4+ and CD8+ central memory population, respectively. No significant gender-related variability of TCR repertoires was identified, and significant impact of chronic cytomegalovirus infection was shown. Our results serve as reference for future studies elucidating clonal TCR dominance of T-cell subsets.

The 10th anniversary of the Junior Members and Affiliates of the European Academy of Allergy and Clinical Immunology.

This year is the 10th anniversary of the European Academy of Allergy and Clinical Immunology (EAACI) Junior Members and Affiliates (JMAs). The aim of this review is to highlight the work and activities of EAACI JMAs. To this end, we have summarized all the initiatives taken by JMAs during the last 10 yr. EAACI JMAs are currently a group of over 2380 clinicians and scientists under the age of 35 yr, who support the continuous education of the Academy's younger members. For the past decade, JMAs enjoy a steadily increasing number of benefits such as free online access to the Academy's journals, the possibility to apply for Fellowships and the Mentorship Program, travel grants to attend scientific meetings, and many more. In addition, JMAs have been involved in task forces, cooperation schemes with other scientific bodies, organization of JMA focused sessions during EAACI meetings, and participation in the activities of EAACI communication platforms. EAACI JMA activities represent an ideal example of recruiting, training, and educating young scientists in order for them to thrive as future experts in their field. This model may serve as a prototype for other scientific communities, several of which have already adapted similar policies.

Clonal drift demonstrates unexpected dynamics of the T-cell repertoire in T-large granular lymphocyte leukemia.

T-cell large granular lymphocyte leukemia (T-LGLL) is characterized by chronic lymphoproliferation of cytotoxic T lymphocytes (CTLs) and is associated with lineage-restricted cytopenias. Introduction of T-cell receptor (TCR) variable ß-chain (Vß) monoclonal antibodies has facilitated identification and enumeration of clonal CTLs by flow cytometry. A highly skewed TCR Vß repertoire identified by flow cytometry is strongly associated with monoclonal CDR3 regions by quantitative sequencing and positive TCRγ rearrangement assays. Therefore, Vß expansions can serve as surrogate markers of CTL clonality to assess clonal kinetics in T-LGLL. We analyzed the TCR repertoire in 143 patients, 71 of which were available for serial measurements over 6 to 96 months. Although the majority (38/71, 54%) maintained a consistent monoclonal expansion, many (26/71, 37%) unexpectedly displayed a change in the dominant clone, whereby the original CTL clone contracted and another emerged as demonstrated by Vß typing. Our results demonstrate that the T-cell repertoire is more dynamic in T-LGLL than recognized previously, illustrating the heterogeneity of disorders under this categorization.