This blog is a way of sharing the information and resources that have helped me to recover my son Roo from an Autism Spectrum Disorder. What I have learned is to view our symptoms as the results of underlying biological cause, which can be identified and healed. I say "our symptoms" because I also have a neuro-immune disorder called Myalgic Encephalomyelitis.

And, of course, I am not a doctor (although I have been known to impersonate one while doing imaginative play with my son)- this is just our story and information that has been helpful or interesting to us. I hope it is helpful and interesting to you!

Saturday, April 11, 2015

Infections can Trigger Mast Cells and Histamine Release

It has recently been discovered that Influenza infection can trigger mast cell activity and that this may be a major factor in the morbidity associated with influenza infection.  It is thought that the severity of some influenza strains is due to an overreaction of mast cells (and other immune cells such as dendritic cells) that causes damage to the lungs that then allows bacterial infections to take hold.  You can read more about this idea here:

Mast Cells and Influenza A Virus: Association with Allergic Responses and Beyond
A post on the blog MastAttack has great information about the role of infections in triggering mast cells and releasing histamine (as well as other mediators).  From the post:

"TLR2 is one of the most well studied and understood of toll-like receptors found on mast cell surfaces. TLR2 is also known as CD282. Substances that bind to TLR2 include many molecules released by bacteria and fungi. Several types of peptidoglycans and found in bacterial cell membranes bind TLR2. In particular, lipoteichoic acid is a potent activator of TLR2. This molecule is found on the surfaces of gram-positive bacteria, like Staphylococcus spp. (Staph, MRSA) and Streptococcus spp. (Strep). Other bacteria that are known to activate TLR2 include Neisseria meningitides, Haemophilus influenzae, and Borrelia burgdorferi, among others. Mycobacteria are also activating to TLR2. Zymosan is found in cell membranes of yeast and binds TLR2. Aspergillus fumigatus (fungi) and several viruses, including Herpes simplex, Varicella zoster,Cytomegalovirus and measles, activate TLR2 responses. Heat shock protein 70 (HSP 70) is released by cells in the body when they are under certain types of stress, and this can activate TLR2.

Multiple studies reported that stimulation of TLR2 with peptidoglycan (a constituent of gram positive bacterial cell membranes) induced degranulation. Stimulation with peptidoglycan induced histamine release as well as cytokine release in a 2003 study (Varadaradjalou 2003). Another study found that peptidoglycan did not cause statistically significant degranulation, but zymosan (a fungal product) and Pam3Cys (a synthetic molecule that acts like LPS, another component of bacterial membranes) did induce significant degranulation (McCurdy 2003). Other studies have not been able to replicate these results."

Here are a few other relevant studies:

Enhancement of IgE-mediated histamine release from human basophils by immune-specific lymphokines.
In this study, it was found that basophils that have been exposed to certain viruses release more histamine in the presence of ragweed IgE than basophils that were not previously exposed to the virus.

Chronic urticaria and blastocystis hominis infection. A case report
In this case study it is found that a parasitic infection is the cause of a woman's chronic hives.

Borrelia burgdorferi Spirochetes Induce Mast Cell Activation and Cytokine Release
Infection with Borrelia burgdorferi, the pathogenic agent in Lyme Disease, can activate mast cells and cause the release of tumor necrosis factor alpha.