What role does Th1 and Th2 have in multiple sclerosis exacerbations?

Here is My Question:
Is an exacerbation of MS the presentation of Th1 or Th2?

Answer:
The Th1 and Th2 you are referring to reflect T-helper cells (1 and 2) which are types of white blood cells that help fight off infections among other roles.  

Th1 cells are primarily involved in cell-mediated immunity (ie, dealing with viruses, etc) while Th2 cells are involved in humorally-mediated immunity (ie, producing antibodies against bacteria, etc).  

This is a gross over-simplification as both are involved in immunity; however, the Th1 and Th2 responses appear to keep each other "in check" so one does not dominate the other (a
"checks and balances" approach if you will).  In general terms, Th1 responses are considered "pro-inflammatory" while Th2 responses are considered "anti-inflammatory".

When these cell types are invoked as part of the conversation in MS,we are typically speaking about the "cytokines" (or chemical signals) that these cell types make to communicate with one another in the immune reaction.  The relative abundance (or lack thereof) in a patient can give us an idea about the state of the immune system in that person.  

For instance, if a relative abundance of pro-inflammatory cytokines are discovered in the blood, this likely represents a state of immune activation to fight off a foreign entity (ie, bacteria, virus, or even a rogue cancer cell).  In multiple sclerosis, it is not entirely clear what sets this off, but the end-product of the inflammation damages myelin and surrounding tissue in the brain and spinal cord.

In multiple sclerosis, the cytokine profile tends to be skewed towards the Th1 response (or more inflammatory) even at rest/baseline.  In the case of an MS attack, the net cytokine profile seems to reflect a Th1 response.  Once again, this is an oversimplification, and both Th1 and Th2 responses are involved.  Much of our approved disease modifying therapies target various stages of the Th1 response for the patient's benefit.

A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente