Bermejo M, Martin-Serrano J, Pedraza MA, Loetscher P, Baggiolini M, Arenzana F, Alcami J; Conference on Retroviruses and Opportunistic Infections.
Program Abstr 6th Conf Retrovir Oppor Infect Conf Retrovir Oppor Infect 6th 1999 Chic Ill. 1999 Jan 31-Feb 4; 6th: 168 (abstract no. 536).
Centro de investigacion Hospital 12 de Octubre, Madrid, Spain.
Objectives To analyze the expression and regulation of CXCR4 in resting and activated peripheral blood lymphocytes, and their relevance in HIV propagation "in vitro". Methods PBLs were activated with PHA (3 microliters/ml), soluble OKT3 antibody (1:1000), PMA (25ng/ml), SEA (20ng/ml) or SDF-1 (200 nM). Membrane and cytosolic CXCR4 expression was measured at different times using flow cytometry and confocal laser scanning microscopy. Mononuclear cell cultures were infected overnight with the X4 HIV strain NL4.3. Surface expression of CXCR4 and intracellular p24 antigen were determinate simultaneously using double labeling techniques. Results Only about 20% of freshly isolated lymphocytes expressed CXCR4 on the cell surface whereas in 80% of resting blood lymphocytes CXCR4 was located intracellulary. Within a few hours in culture, intracellular CXCR4 was translocated to the membrane and was expressed in the large majority of both naive and memory lymphocytes. A decrease in surface expression of CXCR4 was found when lymphocytes cultured overnight for maximal receptor expression were stimulated with PHA, anti-CD3 antibodies, PMA, SEA or SDF-1. Confocal laser scanning microscopy demonstrated the presence of CXCR4 redistribution after activation. The number of cells infected by the X4 HIV strain NL4.3 paralleled the expression of CXCR4 in T lymphocytes. Infected cells expressed higher levels of CXCR4 on the membrane as compared to non-infected cells. Conclusions In resting circulating T lymphocytes CXCR4 is present predominantly in the cytosolic compartment and is reexpresed on the membrane upon culture. After full reexprexion of CXCR4 in culture, T-cell activation downregulates cell surface CXCR4. HIV propagation in culture correlated with the kinetics and intensity of CXCR4 on the membrane of CD4 lymphocytes.
Publication Types:
Keywords:
- CD4-Positive T-Lymphocytes
- Chemokine CXCL12
- Chemokines, CXC
- HIV Infections
- In Vitro
- Lymphocyte Activation
- Oceans and Seas
- Phytohemagglutinins
- Receptors, CXCR4
- T-Lymphocytes
- immunology
Other ID:
UI: 102195304
From Meeting Abstracts