TCR usage and cytokine expression in peripheral blood and BAL T cells

Abstract

SUMMARY T cells are thought to play an important regulatory role in atopic asthma. We hypothesized that human blood and BAL T cell subsets bearing various TCR-Vβ genes might show selective differences in their cytokine profile. Peripheral blood (PB) and bronchoalveolar lavage (BAL) T cells from seven atopic asthmatic and six non-atopic non-asthmatic subjects were stimulated with PMA and ionomycin in the presence of monensin and analysed for TCR-Vβ expression and production of cytokines at the single cell level. The percentage of IFN-γ- and IL-2-producing BAL T cells was elevated compared with PB T cells from both the asthmatic subjects and the non-atopic, non-asthmatic controls. A small percentage of PB and BAL T cells produced IL-4 and IL-5, in asthmatic and normal subjects. In peripheral blood, the percentage of T cells expressing each cytokine was similar in the various TCR-Vβ subsets and in total CD3+ T cells in all normal and six of seven asthmatic subjects. However, there was a substantial degree of heterogeneity in the cytokine profile of BAL TCR-Vβ subsets compared with the total CD3+ T cells. This was more obvious in the asthmatic subjects with a reduction in the percentage of IFN-γ- and IL-2-expressing T cells (five of seven asthmatic subjects) and an increase in the percentage of IL-4- and IL-5-expressing T cells (two of seven asthmatic subjects). These data confirm previous findings of an elevated proportion of IFN-γ- and IL-2-producing BAL T cells while only a small proportion of PB and BAL T cells produce IL-4 and IL-5. Moreover, subsets of BAL T cells, defined by their TCR-Vβ usage, may differ in their cytokine profile compared with the total CD3+ T cells, implying that T cells expressing different Vβ elements may play different roles in regulating the airway inflammation in asthma.