Dynamic Alteration Of Cd4(+) And Cd4(-) Effector/Memory T-Cell Levels In An Asthmatic Mouse Model

Objective: The aim of the current study was to investigate the timing of CD4(+) and CD4(-) effector memory Tcell (TEM) expression levels during an antigen challenge in an asthmatic mouse model. Methods: A total of 51 mice were sensitized with ovalbumin (OVA), then challenged with OVA for 7 consecutive days (asthma group). Another 6 mice were sensitized and challenged with phosphate-buffered saline (PBS) (control group). Spleen and lung cells were harvested, at various time points, up to 30 days after the final challenge. Percentages of CD4(+) and CD4(-) TEM cells (CD3(+)CD4(+)/CD4(-)CD44(High)D62L(neg)), out of the total CD4(+) and CD4(+) T-cell populations, were determined by flow cytometry. Results: Percentages of CD4(+) and CD4(-) TEM cells were higher in OVA-challenged mice than in control mice at 48 hours after the final OVA challenge. In the asthma group, percentages of CD4(+) TEM cells in the lungs increased rapidly during the OVA challenge. Levels were continuously elevated after the challenge ended, reaching a peak (55.69 +/- 2.18%) at day 6 after the final challenge. Levels then declined, gradually, to 20.04 +/- 4.39% at day 30 after the final challenge. Percentages of CDLI: TEM cells in the lungs also increased, gradually, during the OVA challenge period. However, levels peaked (61.97 +/- 3.22%) earlier at 2 days after the final challenge. They then decreased more rapidly to less than 20% at 2 weeks after the final challenge. Conclusion: CD4(+) and CD4(-) TEM cells exhibited different expression patterns during and after the OVA Challenge.