Yesterday I heard a talk by Rolf Zinkernagel who won a Nobel prize together with Peter Doherty in 1996 for the discovery of the MHC restriction in the T cell recognition of antigens. What this means is that a T cell which is monitoring the body for harmful substances does not recognise the antigen (the substance itself) alone but a combination of the antigen with a major histocompatibility complex (MHC) molecule. The MHC molecules were originally discovered through their role in tissue transplantation. In order that a transplant not be rejected the MHC molecules of donor and host should be sufficiently similar. The key work which earned the prize was done in Australia and it was interesting to observe that Zinkernagel (who is originally from Switzerland) speaks English with quite a noticeable Australian accent. The talk was clearly meant to be provocative and the speaker did emphasize on more than one occasion that he was exaggerating. My knowledge of the subject is not good enough to allow me to make a comprehensive judgement of his claims but it was clear that he was presenting a picture far from the usual consensus.
One of the statements in the talk is the one which occurs in the title of this post, namely that fifty per cent of what is in immunology textbooks is wrong. This was complemented with the statements that what is difficult is to know which fifty per cent is wrong and that more than fifty per cent is based on fashion and something else which I do not remember. On a more humble note the speaker said that a similar statement might apply to what was in his lecture. This is not going to cause me to lose confidence in immunology textbooks but it is reasonable to adopt the recommendation not to accept what is in the books uncritically.
Zinkernagel said that from an evolutionary point of view our immune system is designed to work well until we are 25 at the most, which was all that was required to guarantee offspring for our ancestors. It is not clear to me that having some more children could not have resulted in a competitive advantage. It may, however, be that before the invention of agriculture it was impossible to feed many children. He emphasized the important role of the period before and shortly after birth in the development of the immune system. In the first months children are protected by antibodies coming from the mother and the claim was that this has a determining influence on the way the immune system works. At the same time he was critical of the standard picture of acquired immunity, where the reponse to a second infection is faster and stronger than that to the first infection and this is the key to immunity. He also suggested that after an individual has been infected with a pathogen such as measles the antigen remains in the body in some form and continues to stimulate the immune system. This seemed very speculative to me. The lecture contained many comments relating to diverse aspects of immunity (the speaker emphasized the importance of making the distinction between immunity and immunology). One suggestion I found interesting was that by doing intensive research on the relatively benign HIV-2 it might be possible to obtain essential insights for understanding the problem of HIV-1 better.
The lecture hall was very full and this showed that there was a lot of interest in hearing this speaker. On the other hand the questions after the talk were very few and it did not seem to come to a real intellectual engagement between the speaker and the members of the audience asking the questions. Perhaps Zinkernagel has moved so far from the accepted view on many themes in immunology that communication with colleagues has become difficult. Whatever else can be said about this lecture I think it did have the positive feature of stirring up the ideas of the audience and this cannot be a bad thing in science.