Chinese researchers investigating the effect of Platelet Activating Factor (PAF) on the blood-brain barrier, the critical final divide between the sensitive brain tissue and the blood vessels, discovered that a tiny increase in PAF has a double trouble effect on the protective layer.  They found that cells exposed to a minor concentration of PAF for 24 hours died faster and produced an immune system compound that helps carry white blood cells across the walls of blood vessels.

PAF is made with a combination of two chemicals- lysophosphatidylcholine (LPC) and the naturally occuring acetyl Co A.  LPC is an emerging ingredient in vaccines designed to irritate the immune system (a class of compounds called adjuvants) and is as effective as Alum, the vaccination gold standard, at getting the immune system riled up.  The addition of LPC to vaccines in place of alum seems to predict an increase in PAF, which within 24 hours increases the risk of inflammatory cells and chemicals crossing from the blood into the brain. 

As anti-vaccination choice advocates seem to be trumpeting the "safety" of thimerosal and alum, they seem to missing the bigger point.  An increase in adjuvants like LPC has a cascade effect on the body.  We need more research into the effects of that cascade, not more dismissive rhetoric.

Weirong Fang, Xiaohan Geng, Yan Deng, Yunman Li, Erxin Shang, Juan Cen, Peng Lv (2011). "Platelet activating factor induces blood brain barrier permeability alteration in vitro." Journal of Neuroimmunology 230 (1): 42-47. doi:10.1016/j.jneuroim.

Perrin-Cocon L, Agaugué S, Coutant F, Saint-Mézard P, Guironnet-Paquet A, Nicolas JF, André P, Lotteau V. (2006). "Lysophosphatidylcholine is a natural adjuvant that initiates cellular immune responses." Vaccine. 2006 Feb 27;24(9):1254-63.