Accessing Early Differentiation of Virus-Specific Follicular Helper CD4⁺ T Cell in Acute LCMV-Infected Mice

Our research describes reproducible methods for assessing the early phase commitments of virus specific TFH cells, including establishing acute assay infective, multi carmal mouse model, conducting flow cytometry staining, and performing retroviral vector based gene manipulation. Compared to in vitro T-cell stimulation, in vivo stimulation could activate T cells more quickly even in 12 hours and is fully activated for the next retrovirus transduction. Our findings were helping studies exploring the mechanisms underlying the early commitment of various specific TFH cells.

Furthermore, our research will contribute to understanding T-cell dependent humor, humility, and optimizing vaccine design. To begin, obtain a six to eight week old CD45.1 positive smarter mouse and inject it with 200 micrograms of LCMV GP61-77 peptide in 100 microliters of RPMI medium intravenously. After acquiring the splenocytes from the mouse, suspend them in 2%RPMI to achieve a cell density of one times 10 to the eight cells per milliliter and place the tube with cells on ice.

Dispense 50 microliters of cell suspension along with 150 microliters of staining buffer to each well of a round bottom 96 well plate. Centrifuge the 96 well plate at 800G for one minute at four degrees Celsius. And carefully decant the supernatant.

Vortex the plate and add 200 microliters of staining buffer to each well. After pelleting the cells resuspend and incubate them with surface antibody cocktail on ice for 30 minutes in the dark. After washing two times, resuspend the cells in 200 microliters of standing buffer and transfer them into a flow cytometry tube.

Perform flow cytometry analysis to check the activation status of smart test CD4 positive T cells. Then seed one times 10, the six smart CD4 positive T cells per well into a 24 well plate. Spin down the cells at 800 G for three minutes at four degrees Celsius and carefully remove the supernatant medium.

Next, add one milliliter of retrovirus medium and eight micrograms of polybrene to each well. Spin transduce the cells at 800 G for two hours at 37 degrees Celsius. After discarding the retrovirus medium, incubate the cells with one milliliter of pre-warmed 10%RPMI supplemented with interleukin two.

Transfer the cell suspension into a 15 milliliter conical tube and centrifuge it. After discarding the supernatant, resuspend the cells with 2%RPMI to achieve a cell density of one times 10 to the eighth cells per milliliter. For assessing the transduction efficiency, aliquot 50 microliters of cell suspension into a round bottom 96 well plate.

Incubate them on ice with the surface antibody cocktail including CD4, V alpha two and vector tag associated antibody. Wash the cells and perform flow cytometry as demonstrated earlier. Then inject one times 10 to the six CD 45.1 positive smart test CD4 positive T cells to a C57 BL6 recipient mouse intravenously followed by one times 10 to the six plaque forming units of LCMV Armstrong the next day.

After acquiring the splenocytes from the mouse, stain them to check the desired markers. To detect transcriptional factors, incubate the cells with 200 microliters of 2%paraform aldehyde at room temperature for 20 minutes in the dark. Finally perform flow cytometry to detect factors at the early acute LCMV infection stage.

On day three after infection, a balanced bifurcation of follicular helper T cells and T helper one cells among MIGR one SMART two CD4 positive T cells was found. A predominant follicular helper T-cell directed differentiation and enhanced BCL6 expression levels were observed in MigR1 BCL6 Smart CD4 positive T cells.