Publication Analysis 2005-2011
by Kathleen Gransalke, Labtimes 06/2013

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Image: F. Hoffmann-La Roche Ltd.

Measured by the unusually high number of research papers and an even higher number of citations, immunology research seems to be one of the biggest topics in Europe. Most remarkably, not less than four women scientists are among our top 30 most-cited immunologists.

The red-beard sponge, Microciona prolifera, dwells in the Northwest Atlantic, where it attaches to rocks and feeds on plankton. You may be wondering: Why start an article about Immunology with a sponge? But even the most primitive multicellular organism is already able to distinguish between self and non-self, which is the very basic requirement for a functional immune system. Transplantation experiments have shown that sponges happily accept grafts taken from their own kind but reject those of other species. In most sponges this “immune response” is realised through certain receptors at the sponge cell surface, not unlike those of vertebrates, but M. prolifera and certain other marine sponges have come up with something extraordinary – they entrusted specialised cells, called gray cells, with the job. These sponge immunocytes are huge, highly motile and they quickly accumulate at the contact site of xenogeneic grafts and initiate the rejection reaction.

With life getting more and more complex, the immune system had to meet increasingly diverse demands. At some point, one type of “immune cell” simply wasn’t enough. That’s how the mammalian immune system ended up with that bewildering variety of cells in charge of keeping foreigners out and natives in. And whenever scientists think they have finally caught all immune cells, new ones pop up somewhere. One of the more recent additions is a new type of T helper cell called Th9, which produces the cytokine interleukin-9 and “might be involved in pathogen immunity and immune-mediated disease” (Immunol Rev, 252(1):104–15).

A vast number of immune cells and immunologists

As vast as the number of cells involved with immunological processes, is the number of immunologists in Europe. The discipline’s high popularity forced us to make a tiny modification for the nations’ ranking, which is, by the way, based on expert journals filed under the subject category Immunology in Thomson Reuters’ Web of Knowledge database. In contrast to some of the most recently published rankings (LT 6-2012 – LT 5-2013), in which we included any type of publication, we, this time, had to restrict our query to articles, reviews and proceedings papers. The exclusion of those publication types, however, resulted in a slightly higher citation per article value.

All in all, European immunologists published more than 60,000 articles, reviews and proceedings papers between 2005 and 2011 – most of them (7.5%) in the Journal of Immunology. The top three Immunology journals, according to the Impact Factor, are the Annual Review of Immunology (IF: 36.56), Nature Reviews Immunology (IF: 33.13) and Nature Immunology (IF: 26.2).

Comparing our latest publication analysis in Immunology to the one we did six years ago (LT 4-2007) revealed quite little movement in the nations’ ranking. The top six kept their positions, with England firmly holding on to its Immunology crown. In hot pursuit are Germany, France, Italy, the Netherlands and Switzerland. Switzerland also shines with the highest citation per article ratio (27.3) among all contenders; similarly well-cited articles were written in Ireland (25.8) and, surprisingly, Iceland (25.0), placing only 25th according to total citations. Incidentally, the Icelandic paper collecting the most citations (316 out of 3076) is about Innate Immunity of Fish, written by Bergljót Magnadóttir from the University of Iceland in Reykjavik.

As we have observed with many publication analyses before, also with this ranking European immunologists authored more articles than their US peers but couldn’t achieve more total citations and citations per article. Both Europe and the US collected over one million citations. Japan and Canada also did their part to contribute to advances in Immunology. In Japan, Shizuo Akira from Osaka University, is the expert when it comes to pattern recognition receptors, of which the famous Toll-like receptors are an example. These receptors recognise certain microbial molecules like bacterial lipopolysaccharide and kick-start the immunological response. Akira was once the world’s most-cited scientist. Had he been working in Europe between 2005 and 2011, he would have been the uncontested number one in our ranking. His almost 500 papers gathered a staggering amount of 36,000 citations.

A minimum of 5,000 citations needed

But who is the number one of our top 30 most-cited immunologists? For us, recognising real immunologist (self) from a scientist with an interest in some aspects of immunology (non-self) wasn’t as easy as it is for dendritic cells. But we, nevertheless, attempted to devise a few exclusion criteria. Whenever a researcher mostly published papers that dealt with the treatment (guidelines, clinical trials) or the genetic risk factors of a disorder that involves the immune system like arthritis, asthma or HIV, we decided to leave them out. Was it his or her major intention to characterise the pathomechanisms of such a disease, we considered him or her fit for the ranking.

To be counted as one of Europe’s most-cited immunologists, at least 5,000 citations needed to be collected within the seven-year time frame. This is much more than compared to most other rankings and is evidence of the importance of this discipline in the life sciences. Besides the high citation numbers, another number increased significantly, too: the amount of women among the top 30. Not one, not two but four female scientists – Laurence Zitvogel (7th), Erika von Mutius (17th), Maria Roncarolo (26th) and Fiona Powrie (28th) – mix with the usual all-male club at the top.

Looking at institute affiliations reveals that the UK hosts the most (seven) highly-cited immunologists (including one in Wales and another in Scotland). Immunological research is also of high priority in the Netherlands and France – both countries have five researchers placed in our top 30. France can even pride itself with the fact that our top-cited scientist, Guido Kroemer (1st), works at one of the country’s institutes, the Institut Gustave Roussy. The Institut “specialises in research on and the treatment of all types of cancer” and that’s conveniently also the expertise of Kroemer and colleague Zitvogel. Both work on the role of the immune system in cancer and anticancer treatment.

Inflammation, which can be caused by various factors, such as burns, pathogens, radiation, stress or damaged cells, is, scientifically, of interest for a subset of other researchers. Among them is Josef Penninger (10th). One of his projects deals with the question on how malnutrition leads to disorders of the immune system, diarrhoea and intestinal inflammation. Fiona Powrie is also highly fascinated with the gut. By dissecting the interaction between T-cells and dendritic cells and the cytokine network, she wants to understand how the host manages to keep good bacteria alive but kill the bad ones and, like Markus Neurath (27th), what goes wrong in inflammatory bowel disease.

Innate immunity beats acquired immunity research

Since the discovery of Toll-like receptors expressed by cells of the innate immune system, it seems that cells of the acquired immune system have lost a bit of their popularity among scientists. Thus, scientists studying T-cells or B-cells like David Price (20th), Maria Roncarolo and Antonio Lanzavecchia (29th) are few and far between in our top 30. All the higher is the number of innate immunologists, determined to find out exactly how macrophages, dendritic cells or natural killer cells recognise and eliminate bacterial, viral or fungal invaders. Among them, the late Jürg Tschopp (2nd), Siamon Gordon (7th), Mihai Netea (9th), Luke O’Neill (14th), Tom van der Poll (18th), Gordon Brown (21st) and Steffen Jung (25th), who even has one paper together with the discoverer of the dendritic cells, Ralph Steinman.

Yet a few other researchers, Jean-Laurent Casanova (11th), who has a double affiliation with Rockefeller University in New York, and Alain Fischer (12th), turned their attention to primary immune deficiencies. These conditions can be traced back to inborn errors of genes important for immune function, giving carriers a much higher likelihood of contracting an infection. Also among our top 30 is Nico von Rooijen (4th), who still reaps the rewards of having developed a system in the late 1980s that depletes tissues of macrophages and which is still used by many immunologists around the world.

The immune system, innate and acquired, still leaves a lot of room for researchers to indulge their wildest (scientific) fantasies. Who knows what new cell type or signalling pathway are only waiting to be discovered. As a final remark because, just like space, the immunology field is so vastly, hugely, mind-bogglingly big, it is very well possible that we might have overlooked one or the other immunologist. So, if you think you’ve got what it takes to make the top 30 (and you don’t see your name there yet), we encourage you to step forward and give us your citation numbers. Thank you.

View the Tables: Europe...and the World, Most Cited Authors...and Papers

View the Picture: Most Cited Authors

Last Changed: 11.10.2013