It may help to explain my post from yesterday if I put more in lay language. There seem to be two processes going on to account for the immunodeficiency that we see in indolent lymphomas. For all lymphomas, whether node based or not, there seems to be an underlying inflammatory phase (a good example would be the H.pylori infection behind gastric lymphoma). Helper T cells get attracted to the inflammatory reaction and activated to help in antibody production (Th2 cells). As a result there is a shortage of naive T helper cells to be directed to other tasks like responding to Hepatitis B vaccine. The second type of immunosuppression occurs where there are circulating tumor cells as in CLL. Here, cell to cell contact between CLL cells and T helper cells affects the T helper cell finction so that they are unable to make the normal T helper cytokines and start to die, so there is an absolute deficiency of T helper cells and therefore an inability to respond to vaccines.
People should now come up with ideas to remedy this.