Seeking advice on antibody panel design for IL-17A and Foxp3 in Th17/Treg flow cytometry using mouse spleen single cells.

For your panel, I recommend: CD4 (RM4-5, BV510 or APC-Cy7), IL-17A (TC11-18H10.1 or eBio17B7, PE), IFN-γ (XMG1.2, FITC or APC), Foxp3 (FJK-16s, eFluor 450 or Pacific Blue). Also add a Live/Dead or 7-AAD to exclude dead cells. Foxp3 requires a transcription factor-specific permeabilization buffer, not a regular flow cytometry permeabilization buffer; stain surface CD4 first, then after fixation stain Foxp3 and intracellular cytokines, and do not add the antibodies together. The Foxp3 clone FJK-16s gives relatively stable population separation in mouse spleen, but you need to optimize the fixation time.

Domestic flow cytometry antibodies can be used as substitutes, but for transcription factors like Foxp3 and background issues with IL-17A, it is not advisable to blindly replace all with domestic products. My approach is: for CD4 and IFN-γ, domestic clones can be used; for IL-17A and Foxp3, use imported validated clones; if the budget is really limited, find companies like DaYou, Lianke, 4A Biotech, etc., to do small-package trials, and compare positive/negative with imported same clones or same fluorescence. Domestic lead times are generally 3-7 days, while imported single-vial orders typically take 2-4 weeks; if particularly urgent, first ask about stock availability. Panel design also depends on your machine's lasers and filters, so don't just look at the brand.

For your 25 samples, I recommend performing assay validation first rather than running all samples directly. Take mixed normal splenocytes and set up stimulated/unstimulated groups, FMO, and single-color controls to check whether the CD4-positive population is still preserved after Foxp3 fixation and permeabilization. Common issues with poor Foxp3 separation include excessive fixation time, buffer mismatch, or the use of alcohol-containing permeabilization reagents that cause certain fluorochromes to fail. It is recommended to use eBioscience/Thermo Foxp3/Transcription Factor Buffer or BioLegend True-Nuclear, fix at room temperature for 30-60 minutes, and wash after nuclear staining. If the Treg proportion is very low, enrich CD4 first before staining rather than using whole splenocytes directly, which can improve resolution.

For high IL-17A background, perform Fc Block (CD16/32) first, resuspend cells in FBS/PBS before staining, then add antibodies. During stimulation, do not use PMA/ionomycin at too high a concentration; splenocyte density should mainly be 2-4×10^6/mL. After adding Brefeldin A/monensin, stimulate for 4-5 hours, not overnight, as this will increase dead cells. For IL-17A antibody, titration is recommended, starting from half the recommended amount; after adding intracellular antibody, wash 2-3 times with 1× permeabilization buffer to avoid nonspecific staining. Be sure to set up FMO controls, especially for IL-17A and IFN-γ compensation.