Cov kauj ruam tseem ceeb tshaj plaws hauv kev txhim kho cov tshuaj tiv thaiv kab mob hauv lub cev yog qhov ua kom cov neeg T-lymphocyte. Txawm li cas los xij, cov hlwb no tsis tuaj yeem paub txog tus neeg sawv cev txawv teb chaws uas tau nkag mus rau hauv lub cev thiab pib ua lawv txoj haujlwm. Txhawm rau qhib T-lymphocyte, xav tau cov pab tshwj xeeb - antigen-presenting cells (APCs), uas nthuav tawm ib feem ntawm cov khoom txawv teb chaws ntawm lawv qhov chaw raws li ib feem ntawm qhov loj histocompatibility complex ntawm chav kawm thib ob (MHC II).
MHC II yog cov molecules tshwj xeeb uas cov T-helper receptors yog qhov tshwj xeeb.
Lub tswvyim ntawm cov tshuaj tiv thaiv kab mob tam sim no
APCs yog cov pab hlwb ntawm lub cev tiv thaiv kab mob. Ntawm lawv muaj "cov kws tshaj lij" uas tuaj yeem "tig" haiv neeg T-tus pab, tsis yog tsuas yog nthuav tawm cov tshuaj tiv thaiv, tab sis kuj tsim cov teeb liab inducing thaum sib cuag. Activated T-lymphocytes tau txaismuaj peev xwm paub txog txawv teb chaws tawg ntawm daim nyias nyias tsis tsuas yog ntawm APC, tab sis kuj ntawm tag nrho lwm cov hlwb muaj peev xwm nthuav qhia. Txawm li cas los xij, hauv qhov kawg, cov tshuaj tiv thaiv zoo li ib feem ntawm MHC I, tsis yog II.
Native T-helper hlwb, uas tsis tau muaj kev sib cuag nrog cov neeg txawv teb chaws, tuaj yeem cuam tshuam nrog antigen-MHC II complex, uas tau tsim tshwj xeeb hauv APC. Yog li, antigen-presenting cells ntawm lub cev tiv thaiv kab mob yog cov hlwb uas muaj peev xwm nthuav tawm cov molecules ntawm lub ntsiab histocompatibility complex ntawm chav kawm thib ob ntawm qhov chaw.
Cov pej xeem APC yog ib pawg heterogeneous ntawm leukocytes nrog cov lus tshaj tawm immunostimulating zog. Nws suav nrog ntau hom hlwb uas muaj peev xwm nqus tau cov neeg ua haujlwm txawv teb chaws los ntawm phago- lossis endocytosis thiab nthuav tawm lawv mus rau saum npoo raws li ib feem ntawm cov receptors uas tuaj yeem lees paub los ntawm T-tus pab thaum sib cuag. Qhov kawg ua rau tag nrho cov lus teb ntawm kev tiv thaiv kab mob, uas hais txog qhov tseem ceeb ntawm APC.
Kev ua haujlwm ntawm AIC
Kev ua haujlwm ntawm cov tshuaj tiv thaiv kab mob tam sim no tsis yog tsuas yog nthuav tawm xwb, tab sis kuj tseem ua rau muaj cov teeb liab tshwj xeeb uas, thaum sib cuag, ua kom lub cev T cell uas tsis tau ntsib ib qho antigen.
Kev ua haujlwm ntawm AIC muaj ob theem:
- ua tiav - txwv ntawm cov tshuaj tiv thaiv kab mob rau hauv cov khoom me me;
- kev nthuav qhia - embedding antigenic peptide rau hauv MHC thiab xa tawm qhov tshwm simcomplex ntawm daim nyias nyias.
Feem ntau ntawm APC yog tsim nyob rau hauv cov pob txha pob txha.
Thaum ib qho antigen-tam sim no ntawm tes hu rau T-lymphocyte, cov receptors tom kawg paub txog MHC molecule hloov los ntawm kev koom ua ke ntawm txawv teb chaws peptide. Nyob rau hauv cov ntaub ntawv no, cov nyhuv ntawm costimulation yog nqa tawm.
Cov hlwb twg suav tias yog antigen-presenting
Nyob hauv kev tiv thaiv kab mob, cov tshuaj tiv thaiv kab mob yog cov hlwb uas muaj peev xwm ntawm:
- nthuav qhia chav kawm thib ob MHC molecules ntawm daim nyias nyias;
- induce a stimulatory signal rau cov neeg T cell.
Ib qho tseem ceeb tshwj xeeb tshaj yog qhov kev nthuav qhia ntawm antigen ua ke nrog MHC II, uas tuaj yeem lees paub los ntawm T-helper. Yuav luag txhua lub hlwb muaj peev xwm ua tiav cov molecule txawv teb chaws raws li ib feem ntawm MHC 1, tab sis lawv tsis hu ua antigen presenters.
Ntau yam ntawm APK
Hauv kev tiv thaiv kab mob, cov tshuaj tiv thaiv kab mob tau muab faib ua ob pawg loj: kev tshaj lij thiab tsis tshaj lij.
Kev tshaj lij AICs suav nrog:
- macrophages;
- dendritic hlwb;
- B-cells.
Cov pejxeem ntawm cov hlwb dendritic yog qhov dav heev thiab muab faib ua:
- dawb outgrowth epidermocytes (Langerhans cells);
- interdigital thymic cells;
- follicular dendritic cells (FDC).
Txhua tus APCs tshwj xeeb muaj peev xwm xa cov cim costimulatory rau cov neeg T-lymphocytes, uas yog hu uasensitization muaj nuj nqi.
Unprofessional APKs yog:
- hlwb glial hlwb;
- cov hlwb epithelial ntawm thymus thiab thyroid caj pas;
- endothelial vascular hlwb;
- pancreas beta hlwb;
- dermal fibroblasts.
Tsis yog APCs tshwj xeeb tuaj yeem tsim thiab tso tawm antigen-MHC II complexes tsuas yog tom qab stimulation nrog cytokines, uas tuaj yeem yog interferon-gamma thiab lwm yam tshuaj.
Localization thiab migration ntawm APC hauv lub cev
Antigen-presenting cells feem ntau nyob hauv:
- tawv;
- lymph nodes;
- thymus;
- epithelium thiab subepithelial txheej ntawm feem ntau mucous daim nyias nyias.
APCs concentrated hauv epidermis hu ua Langerhans hlwb. Tom qab nthuav tawm cov antigen ntawm qhov chaw ua ke nrog MHC, lawv tsiv mus rau cov qog ntshav hauv cheeb tsam, qhov chaw uas lawv cuam tshuam nrog T-lymphocytes. Lub zog ntawm APC ntawm Langerhans yog ua raws li cov hlab ntsha lymphatic.
Ib tug neeg tshwj xeeb ntawm follicular dendritic cells (FDCs) lub luag haujlwm rau kev nthuav qhia antigen rau B-lymphocytes yog concentrated nyob rau hauv cov ntaub so ntswg lymphoid ntawm mucous daim nyias nyias thiab nyob rau hauv follicles ntawm cov qog nqaij hlav.
Qhov peculiarity ntawm FDCs yog tias lawv tsis tsiv teb tsaws teb rau kev kis kab mob, tab sis yog ib feem ntawm lub network ruaj khov tsim los ntawm lawv tus kheej cov txheej txheem, uas tau txuas rau ib leeg los ntawm desmosomes.
Angen nthuav qhia mechanism
As twbRaws li tau sau tseg saum toj no, kev nthuav qhia antigen ua ntej ua tiav. Thaum xub thawj, cov tshuaj tiv thaiv-tam sim no ntawm tes engulfs tus neeg sawv cev txawv teb chaws los ntawm phagocytosis lossis endocytosis. Tom qab ntawd, nyob rau hauv tshwj xeeb organelles (phagosomes los yog proteosomes), nrog kev pab los ntawm enzymes, antigenic proteins txiav mus rau hauv me me fragments ntawm 8-12 amino acid residues ntev.
Exogenous peptides uas nkag mus rau APC yog cov khoom ntawm phagocyte zom. Hauv cov tshuaj antigen-tam sim no, lawv cov kev txwv ntxiv rau hauv cov peptides me yog nqa tawm. Endogenous peptides tau ua tiav hauv proteasomes.
Tom qab ntawd, cov kab mob antigen koom nrog qhov loj histocompatibility complex. Nyob rau hauv lub spatial conformation ntawm MHC molecule, muaj ib tug tshwj xeeb kab noj hniav nyob rau hauv lub txawv teb chaws peptide yog muab tso rau. Qhov tshwm sim antigen-MHC complex yog thauj mus rau saum npoo ntawm APC membrane.
