CD57+ T cells augment IFN-gamma production in a one-way mixed lymphocyte reaction and their expansion after stem cell transplantation in paediatric patients

Abstract

To clarify the immune response of CD57+ T cells (most of them are CD8+) in peripheral blood (PB) against alloantigens in order to elucidate the T helper 1 (Th 1) immune response, we assessed the role of CD57+ T cells in IFN-gamma (one of the representative Th 1 cytokines) production in a one-way mixed lymphocyte reaction (MLR). In this study, we showed that CD57+ T cells in responder cells were essential for effective IFN-gamma production in allogeneic MLR due partly to the augmentation of the alloresponse of regular T cells. Furthermore, IFN-gamma production in MLR correlated with the proportions of CD57+ T cells in PB regardless of the responders' age. We also showed that the extent of the expansion of CD57+ T cells in paediatric patients after haematopoietic stem cell transplantation (HSCT) was markedly lower than that in adult patients. In addition, CD57+ T cells purified and activated with a combination of cytokines showed a greater cytotoxicity than regular T cells against human umbilical vein endothelial cells. Because IFN-gamma production in one-way MLR is a useful predictor of graft-versus-host disease (GVHD), especially in the acute phase that occurs after allogeneic HSCT, our findings suggested that CD57+ T cells play a role in the development of GVHD and thus may explain the reason as to why a higher donor age is associated with an increased risk of developing GVHD while, in addition, the incidence of severe GVHD in paediatric patients is lower than that in adult patients.

Fig. 1

Decrease in IFN-γ production in one-way MLR due to the depletion of CD57⁺ T cells in responder cells. MLR was performed after the depletion of CD57⁺ T cells from responder PBL. After a 72- or 96-h culture, the IFN-γ levels of the culture supernatants were analysed using ELISA. (a) patients following allogeneic HSCT. (b) adult healthy volunteers (n =5). All data represented are the mean ± s.e. from five independent experiments. *P < 0·05.

Fig. 2

Increase in IFN-γ production in one-way MLR when the proportion of CD57⁺ T cells in responder cells increases. MLR was performed using the cells to adjust the indicated proportions (0, 5, 10 and 20%) of CD57⁺ T cells in whole responder cells from healthy volunteers (n =5). After a 72- or 96-h culture, the IFN-γ levels of the culture supernatants were analysed using ELISA. All data represented are the mean ± s.e. from five independent experiments. *P < 0·05.

Fig. 3

CD57⁺ T cells augment IFN-γ production of regular T cells in one-way MLR. MLR was performed using the purified CD57⁺ T cells, regular T cells (a), the purified regular CD4⁺ T cells, CD8⁺ T cells or either regular CD4⁺ T cells or CD8⁺ T cells added with 20% of CD57⁺ T cells (b) as responder cells from healthy volunteers (n =5). After a 72- or 96-h culture, IFN-γ levels of the culture supernatants were analysed using ELISA. All data represented are the mean ± s.e. from five independent experiments. *P < 0·05.

Fig. 4

IFN-γ production in one-way MLR correlates with the proportion of CD57⁺ T cells in the PBMC of healthy volunteers. MLR was performed using PBMC from healthy volunteers as responder cells. After a 72-h culture, the IFN-γ levels of the culture supernatants were analysed using ELISA. The relationships between IFN-γ production and the responders’ age (a) or the proportion of CD57⁺ T cells in PBMC (b) were examined. The data are based on the findings of several independent experiments from 34 individuals.

Fig. 5

The proportions of CD57⁺ T cells in PBMC increase following allogeneic and autologous HSCT in paediatric patients. The proportions of peripheral CD57⁺ T cells in patients following allogeneic HSCT (n =14) or autologous HSCT (n =8), or in control patients (n =11), were analysed by a flowcytometric analyser. *P < 0·05, **P < 0·01.