Generation of CD28- cells from long-term-stimulated CD8+CD28+ T cells: a possible mechanism accounting for the increased number of CD8+CD28- T cells in HIV-1-infected patients. |
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| Authors: | S Fiorentini F Malacarne D Ricotta S Licenziati A A Solis S Ausenda M De Francesco E Garrafa A Simonini L Imberti A Balsari A Turano A Caruso |
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| Affiliation: | Institute of Microbiology, Department of Experimental and Applied Medicine, Brescia Medical School, Italy. |
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| Abstract: | According to CD28 molecule expression, CD8+ T cells can be classed as CD28bright, CD28dim, and CD28-. The CD28dim T cells were found to derive from mitogenic stimulated CD28-T cells but also from CD28bright T cells through a mechanism of CD28 down-modulation. Moreover, after prolonged in vitro interleukin-2 stimulation, clonal CD28bright, cells showed a CD28dim expression before further evolution to a stable CD28-phenotype. This loss was concomitant with the disappearance of CD28 mRNA. A study of the cytokine production pattern revealed that CD28dim and CD28- T cell clones produced similar levels of type 1 and type 2 cytokines, which differed from those produced by the CD28bright T cell clones. A high percentage of CD28dim and CD28- cells, with similarities in their cytokine production pattern, were found in the blood samples of HIV-infected patients, as compared to healthy donors. The CD28 down-modulation may account for the increased number of CD8+CD28- T cells in HIV-infected patients. |
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