Soluble HLA Class I and Class II Molecules in Relapsing-Remitting Multiple Sclerosis: Acute Response to Interferon-β1a Treatment and Their Use as Markers of Disease Activity

: During relapses in relapsing‐remitting multiple sclerosis (RRMS), serum soluble HLA class I surface antigen (sHLA‐I) levels are reported to either decrease or remain unchanged, whereas serum sHLA‐II levels increase. Interferon‐β1b therapy was recently reported to increase serum sHLA‐I in RRMS. In the present prospective study, solid‐phase enzyme‐linked immunosorbent assay was used to measure sHLA‐I and sHLA‐II in the sera of 21 RRMS patients during a clinical exacerbation, and then six weeks after treatment with high‐dose interferon‐β1a (IFN‐β1a). Pretreatment serum sHLA‐I was significantly lower in patients than in normal controls (P < 0.0005). Pretreatment sHLA‐II was also significantly lower than in normal controls (P= .003) unless enhancing MRI lesions (objectified relapse) were present; then sHLA‐II levels were similar to normal controls (relative increase). Six weeks after initiation of IFN‐β1a treatment, a significant increase in serum sHLA‐I was observed in all 21 RRMS patients (P < .0005). Conversely, serum sHLA‐II decreased significantly after treatment in the entire patient group (P < .0005). The acute effect of IFN‐β1a on serum sHLA‐I and sHLA‐II was observed to be the opposite of that occurring during RRMS relapses. Monitoring of both sHLA‐I and sHLA‐II appears necessary if these molecules are to be developed as RRMS activity markers.