title: Expression of the major rheumatoid factor cross-reactive idiotype in pediatric patients with systemic lupus erythematosus.
abstract: Rheumatoid factor cross-reactive idiotype (RF-CRI) is expressed in high concentrations in the sera of some patients with rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). To determine if RF-CRI is specifically expressed in rheumatic disease or if it is secondary to polyclonal B-cell activation, we examined sera of 23 children with SLE, 16 adolescents with infectious mononucleosis (IM), and age-matched pediatric controls for RF-CRI expression. Concentrations of RF-CRI in serum, determined by an inhibition ELISA, were 24 +/- 17 micrograms/ml (mean +/- SD) in 25 normal children, 31 +/- 17 in 16 young adults with IM, and were significantly increased, 70 +/- 80 micrograms/ml, in the 23 children with SLE (p less than 0.036). Eleven of 23 SLE patients had serum RF-CRI greater than the mean +/- 2 SD for normal children. Ten of 23 SLE sera contained IgM rheumatoid factor (RF) activity. One patient with IM had a borderline elevated RF-CRI level, and 5 IM patients had RF in their sera. The serum IgM concentrations in sera were: SLE (192 +/- 93 mg/dl) and IM (234 +/- 77 mg/dl) sera. These levels were significantly elevated compared to controls (132 +/- 44 mg/dl), p less than 0.031 for SLE and p less than 0.001 for IM, suggesting that polyclonal activation of B cells was present in SLE and IM patient groups. Increased expression of RF-CRI in the SLE patients correlated directly with high titer anti-DNA antibody values (r = 0.3965, p less than 0.05) and RF activity when human IgG (r = 0.5026, p less than 0.05) was used as the RF binding substrate and inversely with serum C3 levels (r = 0.3925, p less than 0.05). RF-CRI expression did not correlate with RF that bound rabbit (r = 0.3123, p greater than 0.05). Increased serum RF-CRI expression is not a result of polyclonal B-cell activation. RF-CRI may be selectively up-regulated in patients with SLE.
authors.affiliation: Division of Allergy/Immunology, Schneider Children's Hospital, Long Island Jewish Medical Center, New Hyde Park, New York 11042.
authors.forename: V R
authors.initials: VR
authors.lastname: Bonagura
authors.forename: N T
authors.initials: NT
authors.lastname: Ilowite
authors.forename: L
authors.initials: L
authors.lastname: Hatam
authors.forename: D J
authors.initials: DJ
authors.lastname: Valacer
authors.forename: J F
authors.initials: JF
authors.lastname: Wedgwood
mesh_terms: D000293:Adolescent; D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D000974:Antibodies, Antinuclear / Q000032:analysis; D002648:Child; D015932:Complement C3c / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D003429:Cross Reactions; D004247:DNA / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007244:Infectious Mononucleosis / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008297:Male; D012217:Rheumatoid Factor / Q000032:analysis*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000974:Antibodies, Antinuclear; D003181:Complement C4; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D015932:Complement C3c; D004247:DNA; D012217:Rheumatoid Factor