Impact of measles virus dendritic-cell infection on Th-cell polarization in vitro.

Interference of measles virus (MV) with dendritic-cell (DC) functions and deregulation of T-cell differentiation have been proposed to be central to the profound suppression of immune responses to secondary infections up to several weeks after the acute disease. To address the impact of MV infection on the ability of DCs to promote Th-cell differentiation, an in vitro system was used where uninfected, tumour necrosis factor alpha/interleukin (IL) 1 beta-primed DCs were co-cultured with CD45RO(-) T cells in the presence of conditioned media from MV-infected DCs primed under neutral or DC-polarizing conditions. It was found that supernatants of DCs infected with an MV vaccine strain strongly promoted Th1 differentation, whereas those obtained from wild-type MV-infected DCs generated a mixed Th1/Th0 response, irrespective of the conditions used for DC priming. Th-cell commitment in this system did not correlate with the production of IL12 p70, IL18 or IL23. Thus, a combination of these or other, as yet undefined, soluble factors is produced upon MV infection of DCs that strongly promotes Th1/Th0 differentiation.