CD107a as a marker of activation in chicken cytotoxic T cells

•A CD107a cell surface mobilisation assay for chicken CTL is set up.•CTL activation is monitored in airways of IBV-infected chickens.•Increased CD107a mobilisation on CTL during IBV infection is observed.

The study aimed to evaluate cell surface mobilisation of CD107a as a general activation marker on chicken cytotoxic T cells (CTL). Experiments comprised establishment of an in vitro model for activation-induced CD107a mobilisation and design of a marker panel for the detection of CD107a mobilisation on chicken CTL isolated from different tissues. Moreover, CD107a mobilisation was analysed on CTL isolated from airways of infectious bronchitis virus (IBV)-infected birds direct ex vivo and upon in vitro stimulation.Results showed that phorbol 12-myristate 13-acetate (PMA) in combination with ionomycin was a consistent inducer of CD107a cell surface mobilisation on chicken CTL in a 4 h cell culture model. In chickens experimentally infected with IBV, higher frequencies of CTL isolated from respiratory tissues were positive for CD107a on the cell surface compared to those from uninfected control chickens indicating in vivo activation. Moreover, upon in vitro PMA + ionomycin stimulation, higher proportions of CTL isolated from the airways of IBV-infected chickens showed CD107a mobilisation compared to those from uninfected control chickens.Monitoring of CD107a cell surface mobilisation may thus be a useful tool for studies of chicken CTL cytolytic potential both in vivo and in vitro.