I did warn you that there would be more posts on the various research examining the immune system in respect of autism. Well, here is another one and it is quite a topic that is covered - eosinophils. Wikipedia has quite a good description of eosinophils here. In brief, eosinophils are white blood cells involved in the body's immune function fighting infections and other foreign materials.
Eosinophils have a little bit of history in relation to autism. There was this paper from a few years back which suggested a role for eosinophils in allergic disease related to autism. Interesting enough. Eosinophils have also found some role in relation to the various research looking at potential gastroenterological comorbidity in some cases of autism.
This case series paper reported the appearance of autism and microscopic eosinophillic colitis in 2 children. The authors suggested several possible reasons for their reported observations including eosinophillic involvement due to food hypersensitivity, reactions to medication, connective tissue disorders, or parasitic infection to name just a few possibilities. This case study reported on eosinophillic esophagitis in a boy with autism and feeding problems thought to be due to the presence of such pathology.
Outside of just case studies, there have been some larger scale findings related to autism. This study by Paul Ashwood and colleagues (remember him from my autoimmunity post) found some quite prominent mucosal eosinophil infiltrate in approaching 30% of their sample group of children with autism and comorbid gastrointestinal problems. The 'inflitrate' part of things means that when ruling out coeliac disease, the authors speculate that something else seemed to cause 'permeability' and the 'leaking out' of eosinophils. Interestingly, they noted that where a gluten- and casein-free (GFCF) diet was followed, the amount of infiltrate was reduced (significantly). Could this be because such diets might affect gut permeability?
There seems to be quite a bit to eosinophils and autism. I would like to think that I can return to them at a later date with more information (hopefully). There are also other sides to eosinophils; their relationship with mast cells as mediators of allergic response and the growing body of work on mast cells and autism; but I am slightly too tired to go into this now, so will leave it for another time.
Good night John-Boy.