Progressive polarization towards a T helper/cytotoxic type-1 cytokine pattern during age-dependent maturation of the immune response inversely correlates with CD30 cell expression and serum concentration

In order to investigate the T cell cytokine profile during age-dependent ma turation of the immune response, we evaluated the cytokine expression of CD 4(+) and CD8(+) circulating cells by how cytometric single-cell analysis af ter non-specific stimulation in vitro, in different age groups of normal in dividuals, from cord blood to adulthood. Moreover, we correlated these lymp hocyte cytokine patterns with the expression/release of CD30, a member of t he tumour necrosis factor (TNF) receptor superfamily, which has been sugges ted to be related to the T helper/cytotoxic (Th(c))2-type immune responses, in order to verify this association in vivo, in non-pathological condition s. The results showed a progressive increase of circulating Th(c)1-type, in terferon-gamma (IFN-gamma)- and/or IL-2-producing T cells along with ageing and, conversely, a stable number, although higher than in cord blood sampl es, of CD4(+)/IL-4(+) T cells in the post-natal groups. In addition, serum levels of soluble CD30 (sCD30) and numbers of circulating CD4(+)/CD30(+) an d CD8(+)/CD30(+) T cells were significantly higher in children aged <5 year s in comparison with those found either in cord blood or in blood from both older children and adults. These data support the concept of a progressive polarization of the Th(c) cell cytokine profile towards the Th(c)1 pattern during age-dependent maturation of the immune response. Moreover, the peak of CD30 expression/release in early infancy before the Th(c)1 shifting occ urs, although not associated with a significant increase of circulating IL- 4(+) T cells, raises the question of the possible relationship in vivo betw een CD30 and Th(c)2-type immune responses.