Correlation Between IFNγ+ and CTLA-4+ Tumor Infiltrating Lymphocytes In Luminal And Non-Luminal Breast Carcinoma
Authors: Parengkuan Irene Lingkan , Mustokoweni Sjahjenny , Kurniasari Nila 
Published: July 2019

ABSTRACT The role of tumor infiltrating lymphocytes (TIL) in breast carcinoma depends on the molecular subtype, especially the expression of the estrogen receptor. A greater mutation load in the non-luminal subtype leads to continuous activation of the immune system resulting in exhausted T lymphocytes. Observational research with a cross-sectional approach was conducted on 40 formalin fixed paraffin-embedded tissue from breast carcinoma at the Anatomical Pathology Laboratory of Dr. Soetomo General Hospital Surabaya during January 2017 -  December 2018. Samples were divided into two groups based on their status of ER expression. The parameter was a positive percentage of TIL immunoreactivity against IFNγ and CTLA-4 antibodies. Percentage of IFNγ+ TIL is higher in the luminal subtype (p =0.001), whereas the percentage of CTLA-4+ TIL is higher in the non-luminal (p =0.001). These expressions were significantly correlated with the molecular subtype of breast carcinoma (p=0.001). A significant correlation between IFNγ+ and CTLA-4+ TIL were found (rs=-0.350, p=0.027). Exhausted T lymphocytes express some inhibitor molecules such as CTLA-4. CTLA-4 (Cytotoxic T-Cell Lymphocyte Associated Protein-4) suppresses immune system function including the activity of IFN-γ as an important molecule in anti-tumor immunity and forms an immunosuppressive and pro-tumor microenvironment. Different level of expressions of IFNγ+ (p=0.001) and CTLA-4 + (p=0.001) TIL were proven to be related to the molecular subtype of breast carcinoma (rs=-0.683, p=0.001; rs=0,501, p=0.001, respectively). The negative correlation between IFNγ+ and CTLA-4+ TIL shows the role of CTLA-4 as an inhibitory molecule to the immune system (rs=-0.350, p=0.027).Keywords : tumour infiltrating lymphocytes, IFNγ, CTLA-4, breast carcinoma,  luminal molecular subtypeCorrespondence to: lingkan.parengkuan@gmail.com ABSTRAK Peran tumour infiltrating lymphocytes (TIL) pada karsinoma payudara berhubungan erat dengan subtipe molekuler, terutama ada atau tidaknya ekspresi reseptor estrogen. Beban mutasi yang besar pada subtipe non-luminal menyebabkan pengaktifan sistem imun terjadi terus menerus dengan hasil akhir terbentuknya subset limfosit T yang kelelahan. Penelitian observasional analitik dengan pendekatan potong lintang ini menggunakan sampel 40 blok parafin dari penderita karsinoma payudara di Laboratorium Patologi Anatomi RSUD Dr. Soetomo Surabaya periode 1 Januari 2017 – 31 Desember 2018 yang dibagi menjadi 2 kelompok berdasarkan ada atau tidaknya ekspresi reseptor estrogen. Parameter penilaian adalah jumlah persentase TIL area tumor invasif yang terpulas positif dengan antibodi IFNγ dan CTLA-4. Ekspresi IFNγ+ TIL didapatkan lebih tinggi pada subtipe luminal (p=0,001), sedangkan ekspresi CTLA-4+ TIL didapatkan lebih tinggi pada subtipe non-luminal (p=0,001). Analisis statistik menunjukkan adanya korelasi signifikan antara ekspresi IFNγ+ TIL dengan CTLA-4+ TIL (rs=-0,350, p=0,027). Salah satu sifat dari sel limfosit T kelelahan adalah mengekspresikan molekul inhibitor sistem imun antara lain CTLA-4 (Cytotoxic T-Cell Lymphocyte Associated Protein-4). CTLA-4 akan menekan fungsi sistem imun dan berdampak pada penurunan aktivitas IFN-γ yang merupakan salah satu molekul penting dalam imunitas anti-tumor sehingga terbentuklah lingkungan mikro yang imunosupresif dan pro-tumor. Hasil penelitian menunjukkan adanya perbedaan ekspresi IFNγ+ TIL (p=0,001) dan CTLA-4+ TIL (p=0,001) pada kedua kelompok yang secara bermakna berhubungan dengan subtipe molekuler karsinoma payudara (secara berurutan mendapatkan nilai (rs=-0,683, p=0,001 dan rs=0,501, p=0,001). Korelasi negatif antara IFNγ+ TIL dengan CTLA-4+ TIL menunjukkan adanya peran CTLA-4 sebagai molekul inhibisi terhadap sistem imun (rs=-0,350, p=0,027).Kata kunci                  : tumour infiltrating lymphocytes, IFNγ, CTLA-4, karsinoma payudara, subtipe molekuler luminalKorespondensi            :lingkan.parengkuan@gmail.com