In an immunological synapse the membrane between the antigen presenting cell (APC) and the t cell touch. They exchange signals so the APC can present an antigen to the t cell. In this case the APC is a dendritic cell that has the right antigen for the t cell and love is in the air.
Here is a picture from the wikipedia article about the immunological synapse between Jurkat T cell expressing GFP-actin (green) and Raji B cell stained with CMAC (blue).
If you want to learn more about immunological synapse here is a publication:
The immunological synapse, Cancer Immunol Res. 2014 Nov; 2(11): 1023–1033.