The B-lymphocyte antigen (CD20) is a suitable target for single-stranded (ss) nucleic acid oligomer (aptamers). The aim of study was selection and characterization of a ssDNA aptamer against CD20 using Cell-Systematic Evolution of Ligands by Exponential Enrichment (Cell-SELEX). The cDNA clone of CD20 (pcDNA-CD20) was transfected to human embryonic kidney (HEK293T) cells. Ten rounds of Cell-SELEX was performed on recombinant HEK-CD20 cells. The final eluted ssDNA pool was amplified and ligated in T/A vector for cloning. The plasmids of positive clones were extracted, sequenced and the secondary structures of the aptamers predicted using DNAMAN® software. The sequencing results revealed 10 different types; three of them had the highest thermodynamic stability, named AP-1, AP-2 and AP-3. The AP-1 aptamer was the most thermodynamically stable one (ΔGAP-1 = −10.87 kcal/mol) with the highest binding affinity to CD20 (96.91 ± 4.5 nM). Since, the CD20 is a suitable target for recognition of B-Cell. The selected aptamers could be comparable to antibodies with many advantages. The AP-1, AP-2 and AP-3 could be candidate instead of antibodies for diagnostic and therapeutic applications in immune deficiency, autoimmune diseases, leukemia and lymphoma.

Background: Acute lymphoblastic leukemia (ALL) is a malignancy with aggressive tumors of immature lymphocytes. T-cell immunoglobulin and mucin-domain 3 (TIM-3) is a Type I transmembrane glycoprotein which is involved in cell proliferation. The objective of this research is to determine the TIM-3 expression in peripheral blood (PB) and bone marrow (BM) of 80 samples of normal and ALL patients. Materials and Methods: The amount of mRNA and protein of TIM-3 measured in the BM and PB the mononuclear layer of samples by real-time polymerase chain reaction and Western blotting. Results: Our findings indicated that relative mRNA expression of TIM-3 in PB and BM of the mononuclear layer of ALL patients was 1.7 and 5 times higher than normals, respectively. We also reported that the protein level of TIM-3 in mononuclear cells of ALL patients was 3.2-fold in BM and two-fold in PB more than normals. Conclusion: In conclusion, this study shows that TIM-3 increases in ALL patients, thus the expression of TIM-3 in tumor cells may be considered as a potential predictive factor in ALL patients, which needs to be explored in future.

Immunophenotypic changes and lineage switch between diagnosis and relapse in acute lymphoblastic leukemia are uncommon and accompanied by poor outcomes. In this report, a 12-year-old boy with diagnosis of pre-B ALL with an aberrant expression of CD 7 is described. Patient was treated with the ALL-BFM 2000 protocol and suffered an episode of relapse with a lineage switch from pre-B ALL to T cell ALL. This report concludes that presence of aberrant expression of CD7 at diagnosis of pre-B ALL can have prognostic value of lineage switch to T cell ALL at relapse.