complement-fixing hidden 19s igm rheumatoid factor ( rf ) , i.e. , 19s igm rf that can be detected in the igm-containing fraction by the hemolytic assay after separation of the serum by acid gel filtration , was evaluated serially ( 3 or more evaluations ) over a 4-year period in 26 children with juvenile rheumatoid arthritis ( jra ) correlating its presence with disease activity .
C0009498
complement
C0229671
serum