Study and identification of clonal T-lymphocyte expansions

DIONISIO, L.; TORREGUITART F.; IOMMI P; ZANELLA L.; GASPARINI N; LANG C.; SANTILLAN N.; AGRIELLO E.

Mar del Plata

Congreso; LXI REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2016

SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC)

T-cell expansions may be due to polyclonal or monoclonal proliferations. Unlike B-cell, does not exist a specific clonality marker, so TCR repertoire is evaluated by Flow Cytometry (FC). Aberrant expression of some markers can help in clonality assessment. The aim is to determine the scope of FC in the study of clonal T-cell expansions. For that, 64 samples obtained from patients with lymphocytosis were evaluated. T-cell markers were studied using a FACSCanto II cytometer and data analysis performed with Infinicyt software and APS tool. Clonality assessment was performed by FC studying TCR Vβ repertoire and by PCR studying TCRγ gene. FISH was used to evaluate rearrangement of ALK gene. 11% of samples showed polyclonal expansions. From clonal ones, 7% resulted γδ+. From αβ+, 50% were CD8+, 44% CD4+ and 6% CD4+CD8+. Most CD8+ clonal cells expressed CD45++, CD3++, CD2+d, CD5+d, CD7+d, CD38+/++, CD56++, associated to LLGG. Patients showed neutropenia and autoimmunity with good prognosis. Even so, we found 2 cases with CD30++, CD5-, CD26+, HLA-DR++, one of them ALK+ and both with poor prognosis, associated to Anaplastic Lymphoma. CD4+CD8+ and γδ samples showed a variable phenotype with clinical features similar to CD8+ group. On the other hand, CD4+ clonal cells showed different phenotypes: 1) CD45++, CD3+d, CD2+, CD5++, CD7+d, CD25-, CD28+, TCL-1++ with hyperleucocytosis and lymphadenophaties, associated to T-PLL, 2) CD3+d, CD25++, CD28++, CD7-, CD5++, CD2+, TCL-1-, with HTLV+, associated with ALLT and 3) CD45++, CD3+d, CD7+d, CD5++, CD2+d, CD25-, CD28+, TCL-1-, skin involvement, associated with Sézary Syndrome. Clonal CD4+ showed poor prognosis, aggressive pharmacological therapy and high mortality. We concluded that FC allowed the identification of clonal T-cells rapidly: TCR repertoire established clonality and phenotype analysis allowed identify clonal entities with different prognosis, evidencing that clonality not always implies malignancy.