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Tai lieu chia se tai: wWw.SinhHoc.edu.vnChng 1

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KHI NIM V MIN DCH HCI. M uSinh vt trong mi trng sng buc phi trao i tch cc vi mi trng tn ti, pht trin v sinh sn. S trao i ny l cn thit tuy nhin n cng thng xuyn mang li cc nguy c c hi cho sinh vt bi v mi trng sng lun cha y nhng tc nhn gy bnh, c bit l cc tc nhn vi sinh vt. that khi cc nguy c ny, trong qu trnh tin ha sinh vt hnh thnh v hon thin dn cc h thng-chc nng bo v cho chnh mnh, mt trong cc h thng l h thng min dch. Min dch hc l mn hc nghin cu nhng hot ng sinh l cng nh bnh l ca h thng min dch. H thng min dch c th chia lm h thng min dch khng c hiu (MDKH) v h thng min dch min dch c hiu (MDH). Thut ng min dch khng c hiu cn c cc tn gi khc nh min dch t nhin, min dch bm sinh. Thut ng min dch c hiu cng c cc tn gi khc nh min dch thu c, min dch thch nghi. Trong lch s tin ha ca h min dch, cc p ng min dch khng c hiu c hnh thnh rt sm v pht trin n lp ng vt c xng sng th cc p ng min dch c hiu mi c hnh thnh. thc hin c chc nng bo v cho c th, hai loi p ng min dch trn hp tc, b tc, khuych i v iu ha hiu qu ca p ng min dch.

II. H thng min dch khng c hiuH thng min dch khng c hiu l hng ro bo v u tin ca c th chng li s xm nhp ca vi sinh vt v cc yu t l khc. Chng bao gm cc thnh phn khng chuyn bit (cn mt s chc nng khc) v chuyn bit thc hin chc nng min dch. 1. Cc c ch khng chuyn bit tham gia vo p ng MDKDH 1.1. C ch c hc S nguyn vn ca da nim mc l hng ro bo v, ngn chn s xm nhp ca vi sinh vt. Mi s tn thng nh trong bng, rch da hoc cc th thut tim truyn u lm tng nguy c nhim trng. Ngoi ra cn c cc hot ng c hc ca lp tim mao nhy ca h thng ng h hp trn nhm loi b v tng kh cc vi khun, cht thi ra ngoi. Cc phn x ho, ht hi cng cho kt qu nh vy. S lu thng v nhu ng ca ng tiu ha, ng tit niu, ng mt ngn cn s pht trin ca vi khun. 1.2. C ch ha hc Trong cc dch tit t nhin c cha cc ha cht c tc dng dit khun khng chuyn bit. V d cc axit bo trong tuyn b, pH thp ca dch m o hn ch s tng trng ca vi khun. toan cao trong dch v c kh nng loi b hu ht cc vi khun. 1.3. C ch sinh hc Trn b mt da, ng tiu ha thng xuyn c mt cc vi khun cng sinh khng gy bnh. Cc vi khun ny ngn cn s pht trin ca cc vi khun gy bnh bng cch cnh tranh cht dinh dng, tit ra cc cht km khun nh colicin i vi vi khun ng rut.

Tai lieu chia se tai: wWw.SinhHoc.edu.vn

Tai lieu chia se tai: wWw.SinhHoc.edu.vnBng 1.1. H thng p ng min dch khng c hiu (khng chuyn bit)

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2. Cc c ch chuyn bit tham gia vo p ng MDKDH 2.1. Cc thnh phn dch th 2.1.1. Lysozym L enzym c trong nc mt, nc bt, nc mi, da (trong huyt thanh hm lng rt thp). Lysozym c kh nng ct cu ni phn t ca mng vi khun, do c kh nng lm ly gii mt s vi khun gram dng. Cc vi khun gram m nh c v bc ngoi l peptidoglican nn khng b ly gii trc tip. Tuy nhin khi v ngoi b thng do tc dng ca b th th lysozym s hip lc tn cng mng vi khun. 2.1.2. Cc protein vim L cc protein c to ra trong pha cp ca phn ng vim nh CRP (C-Reactive Protein, 1 antitrypsin, 1antichymotrypsin, haptoglobin). Trong CRP c sn xut sm nht v c th tng gp 100 ln so vi bnh thng. V vy trong lm sng s dng nh lng CRP huyt thanh chn on v theo di vim ni chung. 2.1.3. Interferon (IFN) L mt nhm cc polypeptid c sn xut do cc t bo nhim vi rut tit ra (Interferon - v ) hay do cc t bo lympho T hot ha (Interferon-). Cc interferon c nhiu hot tnh sinh hc nh cn tr s xm nhp v s nhn ln ca vi rut, km hm s tng sinh ca ca mt s t chc u, c kh nng hot ha cc i thc bo v tng biu l cc khng nguyn ha hp m gip cho qu trnh nhn din khng nguyn ca t bo lympho T. Cc hot tnh ny khng c tnh c hiu vi khng nguyn, c th xy ra vi tt c loi vi rut nn interferon c xp vo h thng min dch khng c hiu. 2.1.4. B th (complement, C) H thng b th bao gm khong 25 loi protein huyt thanh tham gia vo c ch khng t nhin ca c th v c p ng min dch c hiu. Trong huyt thanh b th c sn xut di dng khng hot ng v c hai con ng hot ha b th: - Con ng c in: bt u t C1q v khi ng bi phc hp khng nguyn v khng th (KN-KT), trong khng th thuc loi IgG hoc IgM. - Con ng tt: khng ph thuc vo c ch min dch c hiu (khng cn c s hin din ca khng th v khi ng t C3). Cc vi sinh vt v nhiu cht khc c th li hot ha b th theo con ng tt nh trc khun Gram (+) hay gr (-), vi rut Dengue (st xut huyt, nm, k sinh trng, v mt s cht khc nh polysaccharid vi khun (vi khun lao, ph cu).

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Tai lieu chia se tai: wWw.SinhHoc.edu.vn2.2. Cc thnh phn t bo 2.2.1. Cc bch cu ht

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Chim a s trong bch cu mu ngoi vi (60-70%), c i sng ngn (3-4 ngy). Trong nhm ny bch cu ht trung tnh chim a s v tham gia tch cc vo phn ng vim, chng c kh nng thc bo v trong bo tng c cc ht cha nhiu enzym tiu m, enzym thy phn nh myeloperoxydase, elastase, cathepsin G, hydrolase, lactoferin, collagenase, lysozym. Cc bch cu i toan c vai tr trong khng i vi k sinh trng, phn ng d ng ti ch. Cc bch cu i kim c vai tr tng t nh t bo mast do trn b mt t bo c cc th th i vi mnh Fc ca khng th IgE (FcR). Cc t bo c hot ha khi c hin tng bt cu (lin kt cho) gia cc IgE v khng nguyn c hiu gii phng v tng hp cc hot cht trung gian nh histamin, serotonin, leucotrien. 2.2.2. Bch cu n nhn Cc t bo ny c ngun gc t ty xng lu hnh trong h tun hon, nhng khi xm nhp vo cc t chc th bit ha thnh cc i thc bo vi cc tn gi khc nhau nh t bo Kupffer, t bo bch tuc, t bo xe ngn tay. Chng c kh nng thc bo rt mnh nn c vai tr trong dn dp cc vt l, cc t chc b ph hy, t bo gi ci. Kh nng thc bo ca cc bch cu ht trung tnh , bch cu n nhn / thc bo ph thuc vo s lin kt gia vi sinh vt i vi cc th th b mt ca t bo nh th th i vi C3b. Mi khi vi sinh vt c nhp ni bo trong cc ti, tip theo l s ha mng vi cc th tiu bo. Qu trnh dit khun xy ra theo hai phng thc ph thuc oxy hoc khng ph thuc oxy to ra cc sn phm nh: O2-, H2O2, OCl-, OH- v 1O2, lysozym, lactoferin, cathepsin G, enzym tiu m. Ngoi ra cc t bo n nhn/i thc bo cn tham gia ch ng p ng min dch c hiu bng cch bit ha thnh cc t bo c chc nng trnh din KN cho cc t bo lympho T v tit ra cc cytokin (IL1, TNF,...) m u cho p ng min dch c hiu. 2.2.3. T bo NK (natural killer cells) C mt trong tun hon ngoi vi v c t l t 5-15% cc t bo lympho. V hnh thi th n ging t bo lympho nhng c nhng ht ln trong bo tng, t bo NK khng c cc du n (marker) b mt ca t bo lympho T v t bo lympho B. T bo NK c kh nng dit cc t bo ung th, t bo nhim vi rut m khng cn c mn cm trc v khng b gii hn bi phc hp ha hp m (khng c tnh c hiu).

III. H thng min dch c hiu1. Cc thuc tnh c bn ca MDH 1.1. Tnh c hiu p ng min dch c hiu c ngha l cc khng th hay cc t bo lympho T hiu qu ch c th gn vi khng nguyn hay chnh xc l cc quyt nh khng nguyn c tip xc trc . V d: nu ta tim chng phng bnh un vn th hot tnh min dch ch bo v cho c th chng li bnh un vn m thi. 1.2. Tnh phn bit cu trc bn thn v cu trc l Bnh thng h thng min dch khng to ra p ng min dch gy tn thng cho cc cu trc bn thn trong khi chng li c kh nng thi loi cc cu trc ngoi lai t c th khc (khng cng thuc tnh di truyn).

Tai lieu chia se tai: wWw.SinhHoc.edu.vn

Tai lieu chia se tai: wWw.SinhHoc.edu.vn1.3. Tr nh min dch

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p ng min dch c to ra khi tip xc vi khng nguyn ln th nht khc vi p ng min dch khi tip xc vi chnh khng nguyn ln th hai c gi l p ng th pht : p ng min dch th pht xy ra nhanh hn, mnh hn v c th chuyn th ng bng cch truyn cc t bo lympho mn cm. 2. Cc yu t dch th tham gia p ng MDH Khng th l yu t dch th tham gia vo p ng min dch c hiu v c hai dng: - Dng lu hnh t do trong dch th c kh nng kt hp vi cc khng nguyn (QKN) ho tan c hiu dn n cc thay i sinh hc. - Dng biu l trn b mt cc t bo lympho B, c vai tr l th th khng nguyn ca t bo B cn c gi l cc globulin b mt (sIg). V bn cht, khng th l mt globulin v chng c nhng c im cu trc thc hin c chc nng min dch nn c gi l globulin min dch (immunoglobulin). Cn c vo s di chuyn trn in trng ngi ta cn gi chng vi tn chung l globulin gamma, tuy nhin thc t cn c cc lp di chuyn trn in trng thuc c khu vc globulin v . Cc globulin min dch c kh nng nhn dng rt nhiu quyt nh khng nguyn khc nhau. Khi kt hp vi khng nguyn c hiu, khng th c kh nng hot ha b th v khi b th c hot ha s dn n nhiu hot tnh sinh hc khc nh hin tng opsonin ha to iu kin d cho thc bo, ly gii t bo ch, trung ha cc c t ca vi khun, gy c t bo ph thuc khng th (ADCC). 3. Cc thnh phn t bo tham gia p ng MDH Cc t bo tham gia p ng min dch c hiu ch yu l cc t bo lympho c ngun gc t t bo mm trong ty xng, sau bit ha theo hai con ng khc nhau to nn hai qun th lympho c chc nng khc nhau: t bo lympho T v t bo lympho B. T bo lympho T bit ha tuyn c, chu trch nhim v p ng min dch qua trung gian t bo trong khi t bo lympho B bit ha trong ti Fabricius loi chim v trong ty xng cc ng vt cp cao khc, khi cc th th b mt t bo lympho B kt hp vi cc khng nguyn c hiu v cng vi cc tn hiu khc s lm cho t bo lympho B tng sinh ri bit ha thnh cc tng bo sn xut ra khng th c tnh c hiu tng ng. Ngoi ra thc hin c chc nng min dch c hiu cn c cc t bo khc cng tham gia vo nh t bo trnh din khng nguyn, dng bo, bch cu ht trung tnh..v..v.. 4. Cc phng thc p ng MDH C ch p ng min dch c hiu c th hin hoc bng cch to ra cc khng th hoc qua trung gian ca cc t bo lympho T hoc c hai. Phng thc p ng kiu no ty thuc bn cht v v tr xm nhp ca khng nguyn. 4.1. Min dch dch th Cc khng th c th bt ng cc vi sinh vt, ngn cn kh nng dnh ca vi sinh vt vi cc th th trn b mt ca t bo thc bo, trung ha c t, hot ha b th lm ly gii t bo ch, hin tng opsonin ha lm d cho s thc bo. Khng th c to ra bi cc tng bo do s bit ha v tng sinh dng t bo lympho B c kch thch bi cc khng nguyn. S tng tc gia khng nguyn v t bo lympho B c th xy ra bi hai c ch: ph thuc t bo lympho T hoc khng ph thuc t bo lympho T.

Tai lieu chia se tai: wWw.SinhHoc.edu.vn

Tai lieu chia se tai: wWw.SinhHoc.edu.vn

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Hnh 1.1. C ch hot ng ca globulin min dch i vi tc nhn gy bnh

4.1.1. p ng min dch dch th khng ph thuc t bo lympho T p ng ny c quyt nh bi cu trc ca khng nguyn, c bit l cc phn t c cu trc trng lp vi cc quyt nh khng nguyn lp li, v d nhim trng Streptococcus pneumoniae. Do tnh cht cu trc nh vy s lm cho cc t bo thc bo nhn din d dng cc quyt nh khng nguyn v to nn nhng lin kt cho, kch thch s hot ha t bo ly