CHARACTERISTICS OF IL-6 AND TNF-ALPHA PRODUCTION BY RESPIRATORY SYNCYTIAL VIRUS-INFECTED MACROPHAGES IN THE NEONATE

The production of IL-6 and TNF-alpha and the expression of their mRNA were studied with neonatal (cord blood) and adult blood monocyte-deriv ed macrophages (MDM) after in vitro infection with respiratory syncyti al virus (RSV). Cord blood MDM exhibited production of high levels of IL-6 within 24 hr after infection. Little or no IL-6 production was de tected after 24-48 hr and after in vitro stimulation with inactivated (nonreplicating) virus. Adult blood MDM also produced high levels of I L-6 within 24 hr of RSV infection. Unlike cord blood MDM, adult MDM de monstrated significant activity of IL-6 after 24 hr of infection with live RSV and after exposure to the inactivated virus. The pattern of T NF-alpha production by cord and adult blood MDM after live RSV infecti on resembled closely the pattern of IL-6 production. Both cell types p roduced TNF-alpha in the first 24 hr after infection. However, little or no production was observed after 24 hr of infection and after expos ure to the inactivated virus. The profile of mRNA expression was simil ar to the production of IL-6 or TNF-alpha. mRNA expression occurred ov er a shorter period in cord blood MDM. These observations suggest that inflammatory and immunoregulatory cytokines, such as IL-6 and TNF-alp ha, are produced by neonatal as well as previously primed adult macrop hages. However, neonatal cells may be less efficient in inducing IL-6 production. (C) 1996 Wiley-Liss, Inc.