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原標(biāo)題：中国老头老太xxxxx性

　　動??(dong)態(tài)??(tai)平??(ping)衡??(heng)??，免??(mian)疫??(yi)系??(xi)統(tǒng)??(tong)的??(de)“終??(zhong)生??(sheng)任??(ren)務(wù)??(wu)”　　嬰??(ying)幼??(you)兒??(er)期??(qi)(0～3歲??(sui))??，新??(xin)生??(sheng)兒??(er)免??(mian)疫??(yi)系??(xi)統(tǒng)?(tong)像??(xiang)一?(yi)支??(zhi)未??(wei)經(jīng)??(jing)實??(shi)戰(zhàn)??(zhan)的??(de)“新??(xin)兵??(bing)部??(bu)隊??(dui)”??，先??(xian)天??(tian)性??(xing)免??(mian)疫??(yi)(如?(ru)中??(zhong)性??(xing)粒??(li)細??(xi)胞??(bao)、巨?(ju)噬??(shi)細??(xi)胞??(bao))活??(huo)性??(xing)高??(gao)??，但??(dan)皮??(pi)膚??(fu)、黏??(nian)膜??(mo)屏??(ping)障??(zhang)薄??(bo)弱??(ruo)??，易??(yi)受??(shou)病??(bing)毒??(du)(如??(ru)呼??(hu)吸??(xi)道?(dao)合??(he)胞?(bao)病?(bing)毒??(du)、輪?(lun)狀??(zhuang)病?(bing)毒??(du))侵??(qin)襲??(xi)??。??此?(ci)時??(shi)主??(zhu)要??(yao)依??(yi)賴??(lai)母??(mu)體??(ti)通??(tong)過??(guo)胎?(tai)盤??(pan)和??(he)母??(mu)乳??(ru)傳??(chuan)遞??(di)的??(de)抗??(kang)體??(ti)(如??(ru)IgG、IgA)提??(ti)供?(gong)保??(bao)護??(hu)??。。