title: Time course characteristics of human herpesvirus 6 specific cellular immune response and natural killer cell activity in patients with exanthema subitum.
abstract: The time-course of cell-mediated immunity in exanthema subitum is not well documented. The lymphoproliferative response to purified human herpesvirus 6 (HHV-6) antigen and to phytohemagglutinin was measured and natural killer (NK) cell activities determined in three consecutive specimens obtained biweekly from 18 young children and infants with exanthema subitum. Virus isolation and PCR detection of virus DNA and determination of neutralization antibody to HHV-6 and -7 were also carried out. The magnitude of the HHV-6 specific lymphoproliferative response varied; however, in most cases the time course kinetics revealed a low response in the acute phase with a subsequent gradual increase. In contrast, NK cell activities were high in the acute phase and declined gradually during convalescence. The lymphoproliferative response to phytohemagglutinin did not show a consistent trend in kinetics of time; however, dynamic changes in activity were observed in patients during the acute and convalescent periods. The results suggest that NK cells play a major role in resolving acute phase infection while specific lymphocyte activity develops later. The cause of the delayed development of HHV-6 specific lymphoproliferative response is unknown. The lymphoproliferative response to phytohemagglutinin ratios implied that HHV-6 infection has some impact on host T-cell immunity during the course of exanthema subitum.
authors.affiliation: Pediatric Allergy and Infectious Diseases Society of Sapporo, Kumagai Pediatric Clinic, Sapporo, Hokkaido, Japan. tkuma@mb.infosnow.ne.jp
authors.forename: Takuji
authors.initials: T
authors.lastname: Kumagai
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Mariko
authors.initials: M
authors.lastname: Yoshida
authors.forename: Toyo
authors.initials: T
authors.lastname: Okui
authors.forename: Masaru
authors.initials: M
authors.lastname: Ihira
authors.forename: Nobuo
authors.initials: N
authors.lastname: Nagata
authors.forename: Shoki
authors.initials: S
authors.lastname: Yano
authors.forename: Kimiyasu
authors.initials: K
authors.lastname: Shiraki
authors.forename: Masao
authors.initials: M
authors.lastname: Yamada
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ichihara
authors.forename: Yoshizo
authors.initials: Y
authors.lastname: Asano
mesh_terms: D049109:Cell Proliferation; D005077:Exanthema Subitum / Q000276:immunology* / Q000821:virology*; D005260:Female; D015654:Herpesvirus 6, Human / Q000276:immunology*; D016199:Herpesvirus 7, Human / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007223:Infant; D007694:Killer Cells, Natural / Q000378:metabolism*; D008297:Male; D019349:Roseolovirus Infections / Q000276:immunology; D013997:Time Factors