Background: After heart transplantation, expression of various cytokines can be detected in endomyocardial biopsy specimens both in the presence and in the absence of rejection. In this study we have analyzed the contribution of donor-specific CD8+ cytotoxic T cells to intragraft cytokine expression.
Methods: T cells were propagated from endomyocardial biopsy specimens in medium containing interleukin-2 and interleukin-4. From the T-cell lines obtained, T-cell clones were generated by limiting dilution. A number of 15 CD8+ donor-specific cytotoxic T-cell clones were generated from a single T-cell line and were analyzed for their cytokine messenger RNA expression. The cytokine profile of the clones was studied on the mRNA level by reverse transcriptase polymerase chain reaction.
Results: Almost all clones expressed mRNA for interleukin-1 beta, interleukin-4, and interleukin-10, and 75% of the clones expressed mRNA for interleukin-1 alpha, interleukin-9, and tumor necrosis factor-beta. In about half of the clones expression of interleukin-2, interleukin-6, interleukin-8, and interferon-gamma was detected. Tumor necrosis factor-alpha was only detected in one of the clones. The cytokine profiles exhibited a considerable heterogeneity. The 15 clones had previously been analyzed for their T-cell receptor V beta-gene family expression and T-cell receptor V-D-J region sequence. Homology in the V-D-J regions of the clones indicated that the 15 clones were derived from a limited number of progenitor cells. Interestingly, clones derived from one progenitor expressed a different mRNA cytokine profile.
Conclusions: This study shows that donor-specific cytotoxic T cells can contribute to the spectrum of locally produced cytokines. The cytokine expression of these cytotoxic T cells seems not to be limited to a distinct profile.