Efficient induction of immunoglobulin production in neonatal naive B cells by memory CD4+ T cell subset expressing homing receptor L-selectin.

The humoral response in newborns is mainly restricted to IgM production, which may be attributable to the naive nature of both B and T cells at birth. In light of the current evidence that memory (CD45RO+) CD4+ T cells help B cell differentiation, the present study was undertaken to examine whether a specified population within memory CD4+ T cells could induce the maturation of neonatal naive B cells. In the conventional PWM-stimulated cultures, the generation of IgG- and IgA-producing cells in addition to IgM production by neonatal B cells was significantly enhanced by co-cultures with memory, but not naive, CD4+ T cells.

Absence of bcl-2 expression by activated CD45RO+ T lymphocytes in acute infectious mononucleosis supporting their susceptibility to programmed cell death.

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.

A novel T cell activation antigen identified by monoclonal IMN3.1 antibody and expressed preferentially on human T cells susceptible to apoptotic cell death.

When cultured without appropriate growth factors, most of activated (CD45RO+) T cells expanded in acute EBV-induced infectious mononucleosis (IM) easily die via an apoptotic cell death mechanism, indicating one Ag-driven selection in the periphery. In this work, we attempted to raise the mAb against cell surface molecules, preferentially expressed on T cells entering apoptosis, by immunizing PBMC from an acute IM patient. We obtained one mAb, termed IMN3.

Differential expression of apoptosis-related Fas antigen on lymphocyte subpopulations in human peripheral blood.

The Fas Ag is a newly defined cell-surface molecule that may mediate apoptosis. The antibody against Fas Ag can induce the apoptotic cell death in cell lines expressing this Ag. PBL subpopulations at various ages were here examined for Fas expression by two-or three-color flow-cytometric analyses using anti-Fas mAb.