Corticosteroid resistance in a subpopulation of multiple sclerosis patients as measured by ex vivo dexamethasone inhibition of LPS induced IL-6 production.

We assessed corticosteroid sensitivity in multiple sclerosis (MS) patients compared to control subjects, using an in vitro assay of dexamethasone (Dex) inhibition of lipopolysaccharide (LPS) stimulated-blood interleukin-6 production. Significantly higher concentrations of dexamethasone were needed to obtain 50%-inhibition (ID(50)) of in vitro LPS stimulated interleukin (IL)-6 production (28.4 x 10(-7) M) in relapsing-remitting MS (RRMS) patients compared to chronic progressive MS (CPMS) patients (6.2 x 10(-7) M) or compared to controls (3.0 x 10(-7) M). We also found a trend towards worsening of clinical status over time with increasing corticosteroid resistance. These data suggest that corticosteroid sensitivity may be a factor in the pathogenesis and could be used for prognosis of MS.