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96 HIV-1 Infection of Placental Cord Blood Monocyte-Derived Dendritic Cells
R. M. Folcik, C.-J. Guo*, J. D. Merrill, Y. Li, S. D. Douglas, S. E. Starr, and W.-Z. Ho
The Children's Hosp. of Philadelphia, Univ. of Pennsylvania Sch. of Med., USA
Background: Dendritic cells (DC) are the most potent antigen-presenting cells and have potential to be used as immunotherapeutic agents for HIV-infected patients. In this study, we examined whether monocytes from placental cord blood when cultured with GM-CSF, IL-4, and TNF-a can differentiate into dendritic cells. We then examined HIV infection and receptor expression (CD4 and CCR5) of placental cord monocyte-derived dendritic cells (MDDC) as compared with those of cord monocyte-derived macrophages (MDM).
Methods: Monocytes were isolated from 10 placental cord blood samples and cultured in 48-well plates (0.5 ( 106 cells/well) in the presence or absence of the cocktail of cytokines (GM-CSF 100 ng/ml and IL-4 10 ng/ml). After 5 days, the cells were treated with or without TNF-a (10 ng/ml). MDM and MDDC were then subjected to HIV infection and flow cytometric assay for CD4 and CCR5 expression at day 7, 10, and 13 after the cytokine treatment.
Results: Monocytes isolated from placental cord blood can differentiate into MDDC after 7 days in culture with the cocktail of cytokines, as demonstrated by dendritic cell morphological changes, loss of CD14 expression, and gain of CD83 marker. Although immature MDDC were susceptible to HIV infection, mature MDDC had significantly decreased susceptibility to HIV infection as compared with autologous cord MDM. This resistance of MDDC to HIV infection was due to diminished expression of CCR5 receptor on the cell surface and increased b-chemokine production by cord MDDC. The expression of CXCR4, a major coreceptor for HIV entry into CD4+ T lymphocytes was also down-regulated during differentiation of cord monocytes into dendritic cells. However, CD4, a major receptor for HIV entry into cells, was not affected at both mRNA and protein levels during the cell differentiation.
Conclusions: In summary, our results demonstrated that cord MDDC are much less susceptible to HIV infection than cord MDM. This resistance of cord MDDC to HIV is mainly due to decreased CCR5 expression and increased ?-chemokine production by cord MDDC. These findings may have important implications for the design and development of cord MDDC-based immunotherapy for HIV disease.
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