Human cytomegalovirus infection in foci of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) has been thought to be a disorder of im mune regulation, and increasingly, evidence showing that the tissue damage in LCH involves lymphokines and pro-inflammatory cytokines is reported. We detected human cytomegalovirus (HCMV)-DNA in LCH cells in the foci of LCH l esions by immunohistochemistry, in situ hybridization and PCR, HCMV was det ected in the nuclei and/or cytoplasm of LCH cells in 9 of 27 LCH cases by i mmunostaining. HCMV was probably an early antigen. In situ hybridization re vealed signals for HCMV-DNA only in the nuclei of LCH cells in 10 of the 27 LCH cases. PCR analysis was performed in 20 of the LCH cases, and HCMV-DNA was detected in 7 of these. All 7 positive cases were also positive for HC MV by ISH and IHC. These findings suggested that early phase infection or r eactivation of HCMV occurred in the LCH lesions. HCMV infection may be acco mpanied by impaired cytokine production. Our study also suggested a relatio nship between HCMV infection and expression of TNF alpha. In tissues affect ed by LCH, dermatopathic lymphadenopathy or malignant fibrous histiocytoma and in normal tissues no signals for Epstein-Barr virus-RNA were detected. These findings suggest that in some cases LCH is associated with HCMV infec tion.