title: Absence of bcl-2 expression by activated CD45RO+ T lymphocytes in acute infectious mononucleosis supporting their susceptibility to programmed cell death.
abstract: bcl-2 proto-oncogene encodes an inner mitochondrial membrane protein that blocks programmed cell death (apoptosis). There is now increasing evidence that regulation of bcl-2 expression is a determinant of life or death in normal lymphocytes. We have recently described that activated (CD45RO+) CD4+ and CD8+ T cells in acute infectious mononucleosis (IM) undergo apoptotic cell death on culturing, indicating an activation-driven cell death of mature T cells. In this work, we examine bcl-2 expression by activated T cells in acute IM using a flow-cytometric analysis with an anti-bcl-2 monoclonal antibody (MoAb). It was consistently observed that most T cells from acute IM patients displayed only much less bcl-2, while normal T cells expressed bcl-2 relatively strongly. Multicolor analysis showed that bcl-2-lacking T cells in acute IM were restricted to the CD45RO+ (activated) populations of CD4+, as well as CD8+ T cells. In contrast, the relatively intense levels of bcl-2 were expressed in both CD45RO+ and CD45RO- T-cell populations from normal subjects. This marked difference in bcl-2 expression of CD45RO+ T cells between acute IM and normal controls was also confirmed by Western blot analysis. Activated (CD45RO+) T cells with low bcl-2 expression, but not bcl-2-expressing CD45RO- T cells, in acute IM patients were found to die easily when cultured without added growth factors. However, in normal individuals, both CD45RO+ and CD45RO- T cells were relatively stable on culturing. These findings suggest that lack of bcl-2 expression by activated (CD45RO+) T cells in acute IM might be associated with their susceptibility to programmed cell death.
authors.affiliation: Department of Pediatrics, School of Medicine, Kanazawa University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tamaru
authors.forename: T
authors.initials: T
authors.lastname: Miyawaki
authors.forename: K
authors.initials: K
authors.lastname: Iwai
authors.forename: T
authors.initials: T
authors.lastname: Tsuji
authors.forename: R
authors.initials: R
authors.lastname: Nibu
authors.forename: A
authors.initials: A
authors.lastname: Yachie
authors.forename: S
authors.initials: S
authors.lastname: Koizumi
authors.forename: N
authors.initials: N
authors.lastname: Taniguchi
mesh_terms: D000293:Adolescent; D000328:Adult; D017209:Apoptosis; D015153:Blotting, Western; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007244:Infectious Mononucleosis / Q000473:pathology*; D017493:Leukocyte Common Antigens / Q000032:analysis*; D008213:Lymphocyte Activation; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*
chemical_list: D006133:Growth Substances; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017493:Leukocyte Common Antigens