Human peripheral blood accessory cell: isolation by hypotonic density gradient, functional, and phenotypical...

Area of Science:

• Immunology
• Cell Biology

Background:

• Accessory cells are vital for T lymphocyte activation during immune responses.
• Current methods for isolating accessory cells from human peripheral blood are suboptimal.
• Understanding accessory cell function requires pure cell populations for accurate study.

Purpose of the Study:

• To develop and validate a new density gradient separation technique for purifying accessory cells from human peripheral blood.
• To characterize the accessory cell population responsible for T lymphocyte stimulation.
• To compare the accessory function of purified cells with traditional accessory cells like monocytes/macrophages.

Main Methods:

• A novel density gradient separation method based on hypotonic swelling was employed.
• Peripheral blood mononuclear cells were separated into fractions based on buoyant density.
• Fractions were assessed for accessory cell activity in T lymphocyte proliferation assays.
• Cellular markers were analyzed to characterize the purified accessory cell populations.

Main Results:

• A highly accessory cell-depleted lymphocyte fraction showed minimal response to stimulation.
• A fraction enriched in accessory cells was further separated into Fc-receptor-positive and -negative populations.
• The Fc-receptor-negative fraction exhibited the highest accessory activity for T lymphocyte stimulation.
• These highly active accessory cells displayed characteristics of lymphoid dendritic cells, with distinct morphology and marker expression compared to monocytes/macrophages.

Conclusions:

• The developed density gradient separation effectively isolates accessory cells involved in T lymphocyte activation.
• Lymphoid dendritic cells, specifically the Fc-receptor-negative subset, are potent accessory cells for T lymphocyte periodate stimulation.
• These findings differentiate lymphoid dendritic cells from monocytes/macrophages in terms of accessory function and cell surface markers.