[In vitro cytokine induction in leukocytes by human herpesvirus 7]

Virus infections of the immune system may alter the normal cytokine profile, which leads to symptoms of illnesses. HHV-7 revealed lately has been known as one of the causative agents of exanthem subitum and pityriasis rosea, while its latent infection can be reactivated in immunocompromised conditions. Their pathomechanism has not been explored yet, therefore, the production of some cytokines by separated leukocytes was studied upon primary and secondary infections. After combined treatments with live or inactivated viruses and/or mitogens, the cytokines were quantitated in the supernatant of cells by sandwich ELISA. It was established that, individual cytokines were produced at maximal output at different times postinfection. The quantity of their molecules depended on the primary or repeated infections. Inactivated viral particles also induced cytokine release. Production of IL-2 and IFN-gamma due to mitogen activation could be augmented in primary, but was diminished in secondary infections. Release of TNF-alpha and IL-1 beta was parallel, but the combinatory effect with mitogens increased the quantity of IL-1 beta. HHV-7 induced early IL-10 production, which is known to inhibit cytokine release from helper lymphocytes and consequently might play a role in those acute inflammatory skin diseases mentioned above. In contrast to the related HHV-6 found in severe immunosuppressed conditions, the effect of HHV-7 on the balanced production of different cytokines seems to be related to the mild symptoms of skin disorders caused and that of moderate immunosuppression upon reactivation.