IImmmmuunnoohhiissttoocchheemmiiccaall EEvviiddeennccee ooff AAppooppttoossiiss iinn DDiiffffeerreenntt C Ceellllss ooff HHaasshhiimmoottoo''ss TThhyyrrooiiddiittiiss aanndd GGrraavveess'' DDiisseeaassee TThhyyrrooiiddss Hashimoto Tiroiditi ve Graves Hastal›¤›nda Farkl› Hücrelerin Apoptosisi üzerine ‹mmunohistokimyasal Kan›tlar

Objective: Hashimoto's (HT) and Graves' (GD) diseases are thyroid autoimmune diseases that share similar pathogenic mechanisms. Apoptosis is often related to an autoimmune process and is present in HT thyroid follicular cells. We compared the apoptosis characteristics in these two thyroid diseases considering three thyroid cell types, namely lymphocytes, follicular cells and macrophages. Material and Methods: Nineteen surgically removed thyroids coming from fourteen patients suffering from HT and five patients from GD, have been processed for immunohistochemistry. Apoptosis has been revealed using a terminal deoxynucleotidyl transferase - mediated dUTP nick end-labeling (TUNEL) and an anti active caspase-3 antibody respectively showing DNA fragmentation and activation of the last apoptosis effector. Bcl2, bax and p53 proteins were also immunohistochemically investigated. Results: Lymphocytic infiltration, TUNEL positivity, caspase-3 activation, p53 and bax immunoreactivities were much more present in HT than in GD. Lymphoid cells reacted with anti bcl2 antibody only, with different patterns in HD and in GD. In GD, almost all the follicular cells were immunoreactive with anti bcl2 antibody. In HT, some follicular cells in the vicinity of lymphoid follicles were TUNEL, active caspase-3 and bax positive; on the contrary, far from lymphoid follicles, the follicular cells were bcl2 positive. Our main result showed the presence of numerous macrophages in HT thyroid follicular lumina, expressing strong bax and p53 immunoreactivities along with bcl2, TUNEL and active caspase-3 negativities. Conclusion: Apoptosis is rare in GD thyroids and characteristic of HT thyroid follicular cells in the vicinity of lymphoid follicles. In HT, macrophages initi- ated apoptosis in follicular lumina and seemed either to stop apoptosis before its end or to commit suicide by a caspase-3 independent pathway with- out DNA fragmentation. Turk Jem 2007; 11: 73-8 Özet Amaç: Hashimoto (HT) ve Graves (GH) hastal›klar› tirodin otoimmun hastal›klar› olup ayn› patojenik mekanizmalar› paylaflmaktad›r. Apoptosis s›kl›kla otoimmun olaylara bal› olarak HT tiroid follikül hücrelerinde bulunmaktad›r. Biz bu iki tiroid hastal›¤›nda üç tip tiroid hücresini lenfositler, follikül hücreleri ve makrofajlar› karfl›laflt›rd›k. Gereç ve Yöntem: On-dokuz cerrahi olarak al›nm›fl tiroid (14'ü HT, 5 hasta GH) immunohistokimyasal incelemeye al›nd›. Apoptosis "terminal deoxynu- cleotidyl transferase - mediated dUTP nick end-labeling" (TUNEL) ve anti aktif kaspaz 3 antikor kullan›larak s›ras›yla DNA fragmentasyonunu ve son apoptoz etkeni aktivasyonu bak›larak apoptosis deerlendirildi. Bcl2, bax ve p53 proteinleri de immunohistokimyasal olarak araflt›r›ld›. Bulgular: Lenfositik infiltrasyon TUNEL pozitiflii, kaspaz 3 aktivasyonu, p53 ve bax immunoreaktivitesi HT'da GH'na gore daha fazla bulundu. Lenfoid hücreler yaln›zca bcl2 antikoruyla HT ve GH'da farkl› paternde reaksiyon gösterdi. GH'da hemen tüm folliküler anti bcl2 antikoru ile imunoreaktifdi. HT'da lenfoid follikül civar›ndaki baz› follikül hücreleri TUNEL, aktif kaspaz-3, ve bax pozitifdi. Buna karfl›n lenfoid folliküllerden uzak folliküler hücreler bcl2 poz- itif bulundu. Ana bulgumuz olarak HT'da tiroid follikül lumeninde çok say›da kuvvetli bax ve p53 immunoreaktivitesi ve bcl2, TUNEL ve aktif kaspaz 3 negatiflii gösteren çok say›da makrofaj varl›¤› gözlendi. Sonuç: Apoptosis GH tiroidinde nadir olup, HT için karakteristik olarak lenfoid folliküller çevresinde olur. HT'da makfofajlar apoptosisi follikül lümeninde bafllat›yor ve apoptosisi DNA fragmantasyonu olmadan kaspaz-3'den ba¤›ms›z bir yolda durduruyor görünmektedir. Turk Jem 2007; 11: 73-8 Anahtar kelimeler: Apoptosis, Otoimmun tiroid hastal›klar›, TUNEL, caspase-3, bax, bcl2, p53