T Cell Cytokine Production in Childhood Asthma

A recent asthma audit demonstrated that, 1.4 million children (one in eight) in the UK today are receiving treatment for their asthma, and that this figure has increased six-fold in the last 25 years. The chronicity of asthma has been associated with cytokine-mediated inflammation, in particular from T helper 1 (Th1) and T helper 2 (Th2) cells. Over the past 10 years, a number of studies have tried to unravel the role of T cell cytokines in childhood asthma, as there may well be differences between childhood and adult asthma. Research in this area has been hampered by ethical and practical difficulties. Although a number of studies use whole or separated blood for investigative purposes, the use of T cells obtained from the airways, obtained by bronchoalveolar lavage (BAL), or sputum may be more representative of in vivo cytokine expression. A large body of evidence suggests, that Th2 cytokines are upregulated in paediatric asthma. However, a number of more recent publications propose that Th1 cytokines may also have inflammatory effects in childhood asthma. In particular, IFNγs role in childhood asthma has been clearly documented in studies, from both blood and BAL. Such reports have questioned the concept of the Th1 / Th2 imbalance in such childhood asthma. This review will discuss the current findings on cytokine production from T cells in children with atopic asthma, and attempt to unravel the cytokine complexities in childhood asthma.