There was very much a question of the day, whether the immune system is- how it comes to be- become tolerant of the parts, the variable parts of an antibody molecule, because antibody molecules occur in all sorts of new varieties all the time and the immune system basically shouldn't react against them, but it can do under some circumstances, and that, connected up with an idea of the time about the network, the idiotypic network of the Nils Jerner, so we contributed a little bit to that. We worked on co-operation between T-cells, between cytotoxic T-cells, the T helper cells, and that ended up as the last hurrah of what could be done by adoptive transfers without really doing very much in vitro. It was actually a huge experiment which could have been conducted very much more easily in vitro, but rightly or wrongly, I thought it was important that it should be done in vivo, and we did it and we showed that- demonstrated that form of co-operation [of Bs], a combination sometimes called the three cell cluster theory, where one dendritic cell has two different T-cells which get together in its mesh. We worked quite hard to show that the famous bridge which we were talking about just now, the connection between the T- and the B-cell, did not need to be, to involve, a single molecule. It could involve a set of proteins, or antigens, which were co-processed in the immune system. The B-cell could take up a portion of a bacterium or a portion of a foreign cell, and could drive B-cells- could drive the response of helper T-cells which recognised only one part of it, and the antibody recognised some unrelated molecule. All that was needed was they should be physically linked, and that has become eventually the basis of a new form of vaccination. The contribution which we made to that may have been slight but I think it was actually quite near the- the basis of conjugate vaccination, and conjugate vaccination is when you are trying to immunise a child against a bacterium that has a polysaccharide cell wall, for example, haemophillus influenza. You can drive that response much more effectively if the extracted polysaccharide, you extract the polysaccharide. That can be used for many years as a vaccine, immunogen as a vaccine, but it wasn't a very good vaccine, it did not make antibodies very well and particularly children- were not protected for a long time. But if the carbohydrate was conjugated to another protein which was recognised by T-cells, it became much more effective, and those conjugate vaccines are used now world-wide for these encapsulated bacteria. Meningococci are another group which are being tackled in the same way.