Researchers in Newcastle and Singapore have identified a new type of white blood cell which activates a killing immune response to an external source—providing a new potential target for vaccines for conditions such as cancer or Hepatitis B.

Publishing in the journal Immunity, the team of researchers from Newcastle University in collaboration with A*STAR's Singapore Immunology Network (SIgN) describe a new human tissue dendritic cell with cross-presenting function.

Dendritic cells (DCs) are a type of white blood cell that orchestrate our body's immune responses to infectious agents such as bacteria and viruses, as well as cancer cells. They are also very important for eliciting the immune response generated by vaccines.

DCs kick start an immune response by presenting small fragments of molecules from micro-organisms such as bacteria and viruses, or from vaccines or tumours, called antigens on their surface. This leads to activation of another white blood cell subset called T cells, which specialise in killing cells and are crucial for eliminating cancerous or infected cells. Most cells are only able to present antigens from within themselves, and so will only elicit an immune response if they are infected themselves. Only a specialised subset of DCs is able to generate a response to an external source of antigen, for example bacteria, vaccines and tumours.

The identity of human tissue DCs that are capable of presenting external antigen to activate the cell-killing response by T cells—a process termed 'cross-presentation'—has remained a mystery. Their discovery, as revealed by this research, will help scientists to design better targeted vaccine strategies to treat cancer and infections such as Hepatitis B.

"These are the cells we need to be targeting for anti-cancer vaccines," said Dr Muzlifah Haniffa, a Wellcome Trust Intermediate Fellow and Senior Clinical Lecturer at Newcastle University. "Our discovery offers an accessible, easily targetable system which makes the most of the natural ability of the cell."

The researchers also showed for the first time that dendritic cell subsets are conserved between species and have in effect created a map, facilitating the translation of mouse studies to the human immune system.