CD4 and asthma: Supporting evidence for this model comes from primary human dendritic/T cell coculture experiments which demonstrated that cell-free fecal extracts of 1-month-old infants at high risk for asthma promoted expansion of CD4+IL4+ T-helper 2 (Th2) cells and increased interleukin 4 (IL-4) production while simultaneously reducing CD4+CD25+FoxP3+ regulatory T-cell frequency [4].