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BOALA MIXTA DE TESUT CONJUNCTIV.pdf

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Etiopatogenie<br />

Conceptul actual de colagenoza mixta este legat de raspunsul imun<br />

fata de constituientii nucleului celular, ribonucleoproteina U1 (U1-RNP),<br />

care se traduce prin prezenta anticorpilor antinucleari cu aspect patat<br />

la imunofluorescenta si anticorpii anti-(U1)snRNP.<br />

RNP sunt formate dintr-o asociere de acizi nucleici (ARN) si polipeptide<br />

si sunt implicate in maturarea ARN pre-mesager in nucleul celulei<br />

(splicing) spliceosom<br />

Exista mai multe tipuri de RNP:<br />

- snRNP (small nuclear ribonucleoproteins), care tin de (U1)snRNP si<br />

proteinele sistemului Sm<br />

- hnRNP (heterogen nuclear RNP)<br />

Anticorpii anti-(U1)snRNP din colagenoza mixta sunt specifici<br />

proteinelor care le constituie: proteina 70 kD (inainte denumita 68 kD),<br />

proteina A si proteina C. Aceste polipeptide sunt asociate la (U1)-ARN<br />

si determina raspunsul imun specific.<br />

In colagenoza mixta, caracteristicile serologice sunt in raport cu<br />

raspunsul imun impotriva spliceosom (distinct fata de alte<br />

colagenoze)

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