I had remembered reading that they could increase during a flare, but when I researched again recently (for someone on another forum), this is what I found:

"Oligoclonal bands (OCB) are not unique to MS. In general, CSF OCBs are found in over 90% of MS patients, 30% of patients with central nervous system inflammatory and infectious disease, and 5-10% of other, noninflammatory neurological disorders.

In MS, once OGBs appear, they may increase in number but do not disappear. OGBs do not correlate with severity, duration, or disease activity in MS.

Myelin basic protein is different than OGBs. MBP usually rises during an acute exacerbation and then levels tapers off. Both parameters are tested in CSF in cases of suspected MS. They are used in addition to other information such as history, physical exam, MRI, EPs to establish a diagonosis of MS."

http://www.medhelp.org/forums/neuro/archive/7566.html

"Approximately 79%-90% of all patients with multiple sclerosis have permanently observable oligoclonal bands."

"The presence of one band (a monoclonal band) is not considered serious and may simply be normal. More bands may reflect the presence of a disease. The bands tend to disappear from the spinal fluid as a person recovers from the neurological disease."

http://en.wikipedia.org/wiki/Oligoclonal_bands

So I guess they reduce after the inflammatory process with "other" conditions/diseases, but not in MS.

Cherie