Lifespan of human memory T-cells in the absence of T-cell receptor expression

Umeki S, Kusunoki Y, Cologne JB, Iwamoto KS, Hirai Y, Seyama T, Ohama K, Kyoizumi S
Immunol Letters 62(2):99-104, 1998

Summary

To evaluate the intrinsic lifespan of human memory T-cells in the absence of T-cell receptor signaling, we used radiation-induced mutant CD4⁺ T-cells lacking surface expression of TCR/CD3 complex as an in vivo cell marker. We analyzed the long-term kinetics of TCR/CD3^– mutant T-cells among CD4⁺CD45RA⁺ naive and CD4⁺CD45RA^– memory T-cell fractions in peripheral blood of gynecological cancer patients receiving radiotherapy. Both the proportion and number of these mutant T-cells decayed exponentially with time following radiotherapy. The estimated half-life of mutant memory T-cells was 2 to 3 years and did not differ from that of mutant naive T-cells. These results indicate that the lifespan of mature CD4⁺ T-cells is limited regardless of their memory or naive phenotype in the absence of TCR/CD3 expression. This finding may suggest that continued T-cell receptor signaling is required for lifetime maintenance of human memory T-cells.