Human fetal retinal pigment epithelial cells induce apoptosis in the T-cell line Jurkat.

Abstract

PURPOSE:

To investigate the mechanism(s) involved in human fetal retinal pigment epithelium (HFRPE)-mediated T-cell death.

METHODS:

Pure HFRPE cells were isolated and cultured. Normal and interferon (IFN)-gamma-activated HFRPE from early and late in vitro passages were incubated with cells from the human T-cell leukemia line Jurkat (Jkt). Cultures were pulsed with [3H]-thymidine to measure Jkt cell proliferation. Jkt cells were evaluated for apoptosis either by staining with an ethidium bromide/acridine orange mixture (AO/EB) or with Annexin V-phycoerythrin. The role of Fas ligand (FasL) molecule in HFRPE-mediated apoptosis was assessed by using a mutant Jkt cell line (DD3), which is deficient in Fas-mediated signaling. The involvement of the antiapoptotic human gene bcl-xL was determined by using Jkt cells that were stably transfected with bcl-x(L). The role of cell- cell contact in the induction of apoptosis was evaluated in a transwell system in the presence or absence of neutralizing antibodies against IFN-gamma and tumor necrosis factor (TNF)-alpha.

RESULTS:

HFRPE cells inhibited the proliferation of Jkt cells by inducing apoptosis through a FasL-independent pathway. Passaging and IFN-gamma activation strengthened the inhibitory effect of HFRPE cells on the proliferation of Jkt cells. At lower HFRPE passages (P2), bcl-alphaL, overexpression rescued the HFRPE cell-mediated apoptosis. The separation of the cells by the transwell system did not affect the HFRPE cell-mediated suppression. This suppressive effect was not mediated by the secretion of IFN-gamma or TNF-alpha molecules.

CONCLUSIONS:

HFRPE cells suppressed the proliferation of Jkt cells by inducing apoptosis. HFRPE cells induced a stronger inhibitory effect on Jkt cells at higher in vitro passages. The HFRPE-induced apoptosis was not mediated through the FasL/Fas pathway or through the secretion of the apoptosis-inducing cytokines IFN-gamma and TNF-alpha. The bcl-xL gene may play a role in preventing HFRPE cell-induced apoptosis in Jkt cells. These combined results suggest that the HFRPE-mediated suppression of primary T cells may also be mediated by the induction of apoptosis. Therefore, the retinal pigment epithelium may play a role in the induction of immune privilege in the subretinal space.

• Authors: L Farrokh-Siar, K A Rezai, R T Semnani, S C Patel, J T Ernest, E J Peterson, G A Koretzky, G A van Seventer
• Journal: Investigative ophthalmology & visual science (Invest Ophthalmol Vis Sci) Vol. 40 Issue 7 Pg. 1503-11 (Jun 1999) ISSN: 0146-0404 [Print] United States
• PMID: 10359333 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• BCL2L1 protein, human
• Cytokines
• FASLG protein, human
• Fas Ligand Protein
• Fluorescent Dyes
• Membrane Glycoproteins
• Proto-Oncogene Proteins c-bcl-2
• bcl-X Protein

Topics

• Apoptosis
• Cell Communication (physiology)
• Cell Division
• Cell Separation
• Cell Survival
• Cells, Cultured
• Coculture Techniques
• Cytokines (physiology)
• Fas Ligand Protein
• Fetus (cytology)
• Fluorescent Dyes
• Gestational Age
• Humans
• Jurkat Cells (metabolism, pathology)
• Membrane Glycoproteins (physiology)
• Pigment Epithelium of Eye (cytology, physiology)
• Proto-Oncogene Proteins c-bcl-2 (physiology)
• bcl-X Protein