CD4 and infection: For example, although Th1-type cellular immune responses have previously been observed in filariasis patients with filarial lymphedema63, infection with helminths is typically associated with polarization towards a classical Th2-type humoral response or, in some cases, a more refined CD4+ phenotype, such as Th9, Th17, Th22 or immunosuppressive Tregs (reviewed in64).