    Sentence t: At wha age. do ji ‘immune iespionses  typically begin t to.decline?    ‘Sentonde 2:"Th ability of ie immime “nee  torespond'to pathogens is diminishéd in both:  the “young ind:"the’ elderly,::with: immune  responses beginning’ to decline at around-50,  "years of.age due to imintinosenéscence:    