I've just started a free online Fundamentals of Immunology course with Rice University, part of the EdX onliine programme founded by Harvard, MIT and others. It's not exactly a stroll in the park, but I think its about as accessible an immune course as you can hope for, and there is still time to enroll. Immunology comes up time and again in mecfs studies but is a fiendishly difficult subject to understand. This course, by the wonderful and rather eccentric Dr Alma Novotny makes it accessible. For instance, she introduces a lecture about 'myeloid cell lines' as "potentially terminally-boring", but makes it memorable with artwork like this (a basophil cell) Don't be fooled into thinking this is a joke course - it's got all the biological detail (sadly, it can't be avoided), but in a very digestible way. Here's her intro video: One of the main subjects in the first week is the difference between the innate and the adaptive immune system. The adaptive system is the bit most people are probably familiar with, typified by the production of antibodies against bugs by B-cells. The innate is a bit more primitive - but is good to go from day 1, so keeps you alive while your bodies slowly gets the antibody response going. The innate system works by recognising patterns - what pathogens look like in general eg it recognises "virus" but not influenza. Here is Novotny's brilliant way of explaining this pattern-recognition system of the innate immune system: Yes, that's her, dressed as a bank robber. Her point was that if you walked into a bank and saw someone dressed like that, you would recognise danger. You might never have been in that bank before, or seen that person before, but you instantly recognise the pattern of danger. That's how the innate system works. CD4, CD8, CD22 - the system from Hell You may be vaguely aware of terms like "CD4" and "CD8" to describe types of immune cells, but what do they mean? A CD is cells-surface marker that helps identify the type of cell. The history of it explains why it's so confusing: CD stands for Cluster of Differentiation (very helpful). Basically, immunologists use a bit of kit called Flow Cytometers to separate different types of immune cells, causing them to cluster together into similar groups - hence 'Cluster of Differentiation', or CD. The particular number of the CD marker comes simply from the order in which the cell type was found eg CD4 cells were the fourth type of cell to be categorised this way, CD8 the eighth. So the CD system reakky is a nightmare and you are confused for a reason. Btw, CD4 cells are T Helper cells while CD8 cells are Cytotoxic T cells - the course will tell you what they do and why they matter. Fundamentals of Immunology You will need some biology for this (High school probably ok) and the estimated workload is 7-10 hours a week, though it might be quite a bit less if you already know some immunology. Copyright: the images have been screen grabbed from the videos on youtube to illustrate the point, but please don't reproduce without permission from Rice University.