Relationship between tumor associated macrophages and cytotoxic T lymphocytes in rat liver carcinoma

Abstract

Objective To investigate the influence of tumor associated macrophages on cytotoxic T lymphocytes (CTL) infiltration and apoptosis in rat liver carcinoma.Methods Walker-256 Wistar rat hepatoma models were established.Then rats were randomly divided into three groups:group A (clodronatelipsomes by intraperitoneal injection) ; group B (PBS-lipsomes by intraperitoneal injection) ; group C (normal saline by intraperitoneal injection).Animals were killed at the 12th day after treatment.The tumor volume was measured,and the number of positive cells of CD68,CD8,CD163,and Granzyme B was detected by using immunohistochemical method,respectively.The apoptosis of CD8 + T cells in tumor tissues was tested by the method of double staining with immunohistochemistry and TUNEL.Results ( 1 ) There was no significant difference in tumor volume among groups A,B and C ( P ＞ 0.05 ) ; (2) There was significant difference in CD68 positiv cells between groups A and B,CDE163 positive cells between groups A and B,CD8 positive cells between group A and B or between groups A and C; and Granzyme B positive cells between groups A and C (all P ＜0.05).The number of CD68 and CD163 positive cells in group A was less than in groups B and C.The number of CD8 and Granzyme B positive cells in group A was more than in groups B and C ; (3) There was a negative correlation not only between the positive cells of CD68 and CD8,but also between CD163 and Granzyme B positive cells.However,there was no correlation between the positive cells of CD68 and Granzyme B,as well as between the positive cells of CD163 and CD8 ;(4) There was significant difference in apoptosis rate of CD8 T cells between groups A and C group (P ＜0.05).Apoptosis rate of CD8 T cells in group A was lower than in groups B and C.Conclusion Clodronate liposome can deplete macrophages of rat liver carcinoma tissues effectively.After macrophages were depleted,the number of CTL was increased and the apoptosis rate of CTL was decreased in rat liver carcinoma.Tumor associated macrophages can promote apoptosis and inhibit killing activity of cytotoxicity T lymphocyte,and play an important role in tumor development. Key words: Tumor associated macrophage; Cytotoxic T lymphocyte; Infiltration