Aime and Background. The aim of this study was to evaluate let-7 family members expression in activated naïve CD4⁺ T cells and IL-2 induced cells. Let-7 family has oncogenic and tuomor suppressive activity in different cells. 

Methods. Naïve CD4⁺ T cells were activated by anti-CD2, CD3, CD28 microbeads. After 3 days, the activated cells stimulated by IL-2(0.75ng/ml). after 72h total RNA extracted the cells and c-DNA synthesis and Q-RT-PCR performed by miRCURY LNA^TM universal RT miRNA PCR kit. miRNA expression analyzed by geneX software and ∆∆Ct method.

Results. Five members of let-7 family over-expressed in activated cells compared with IL-2 induced cells. Targets Predicted by miRDB and miRanda software including families of DUSP, PTPN and SOCS that two first families inhibit TCR signaling and latest suppress JAK/STAT pathway.

Conclusion. It appears that let-7 family play important role in clonal expansion of activated CD4⁺ T cells by specific genes suppression in post-transcriptional levels for appropriated immune response.