A team of researchers from ULg is studying “Natural Killer” (NK) cells. These cells, which are still relatively unknown, are lymphocytes capable of spontaneously killing certain cells that are infected by a virus as well as some cancerous and metastasizing cells. One of the challenges of modern immunotherapy will be to better understand their functioning in order to succeed in maximizing their action.

Scientists at the Experimental Pathology Laboratory of The Infection, Immunity and Inflammation Unit of the GIGA-Research Institute of the University of Liège, under the supervision of Nathalie Jacobs, research associate at the F.R.S-FNRS, have published two papers on this fascinating subject. The first, a journal article co-signed as first author by Inge Langers (1) and Virginie Renoux, retraces the advances in understanding of atypical cells since their discovery in the 1970s and their role in the fight against tumors and metastasis as well as against virus infection. The second publication by Virginie Renoux (2), which made the cover of the European Journal of Immunology in November 2011, studies the role of NK cells against the human papillomavirus, a virus which can cause cervical cancer.

These are two promising publications which represent another step in the fight against one of the major diseases of our time and which aim to understand or at least reveal part of the major role played by those human cells that act as first-class allies and protectors against viral infections and cancers.

A bridge between two types of defense against attack

In the case of invasion by a pathogenic agent, the body defends itself in two ways.

• In an “innate” way (innate immune response): this is a quick response due to the recognition of patterns common to several pathogens or PAMP (pathogen-associated molecular patterns).
• In an “adapted” way (adaptive immune response): a process of education and adaptation enables T and B lymphocytes to recognize a particular pathogen or tumor cell due to their specific receptors. This response is slower to activate itself and requires the intervention of the innate response but it develops a memory allowing a quicker response in the case of a second aggression by the same pathogen.

So what can be said about these famous NK cells which resemble lymphocytes but which do not have the same specific recognition receptors as their well-known “cousins”? And also, what can be said about their ability to spontaneously kill cancerous cells or cells infected by a virus and, above all, how do they manage to recognize and lyse them? All these questions that remained unanswered for a long time at first led to the NK cells being given the somewhat unglamorous name of “null lymphocyte”, because they did not have any known receptor and were therefore supposed to be without any sophisticated recognition system or memory.

(1) I. Langers,V. Renoux, M. Thiry, P. Delvenne, N. Jacobs. (2012, April). Natural Killer cells -  role in local tumor growth and metastasis. Biologics: Targets and Therapy.http://hdl.handle.net/2268/113249
(2) V. Renoux, B. Bisig, I. Langers, E. Dortu, B. Clemenceau, M. Thiry, C. Deroanne, A. Colige, J. Boniver, P. Delvenne, N. Jacobs. (2011). Human papillomavirus entry into NK cells     requires CD16 expression and triggers cytotoxic activity and cytokin secretion. European journal of immunology, 41(11), 3240-3252. http://hdl.handle.net/2268/97398