Consumption of erythrocyte CR1 (CD35) is associated with protection against systemic lupus erythematosus renal flare

Clin Exp Immunol. 2006 Feb;143(2):274-80. doi: 10.1111/j.1365-2249.2005.02983.x.


Erythrocyte complement receptor type one (E-CR1) is thought to protect against immune complex (IC) disease through interactions that lead to E-CR1 consumption, and low E-CR1 levels are characteristic of systemic lupus erythematosus (SLE). The purpose of this study was to test the hypothesis that E-CR1 consumption can predict or mark SLE flare. Recurrently active SLE patients [n = 43; 28 with past or present major renal manifestations (SLER) and 15 without (SLENR)], were evaluated every 2 months by detailed protocol testing (mean follow-up 22 months), including direct measurements of E-CR1 levels using a radioimmunoassay. In all patients, detectable E-CR1 levels fluctuated widely through acute periods of consumption and regeneration, preventing the use of any single value as a baseline. However, when individual chronic baseline values were used, determined as the mean of all E-CR1 values 4 months or more from a flare, a clear trend was observed. In 16 of 16 instances of non-renal flare in SLER patients, E-CR1 levels decreased at flare (mean decrease 34%, P < 0.0001). In contrast, no consistent difference was observed for flare in SLENR patients or for renal flare in SLER patients. Changes in E-CR1 levels did not correlate with plasma CR1 levels. In conclusion, single occurrences of E-CR1 consumption did not generally predict or mark SLE flare. However, compared to the average E-CR1 levels measured during no-flare intervals, E-CR1 consumption in SLER patients at flare was strongly associated with freedom from signs of renal involvement. We postulate that E-CR1 consumption reflects E-CR1 function that includes protecting against SLE nephritis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Complement C3 / analysis
  • Complement C4 / analysis
  • Erythrocytes / immunology*
  • Female
  • Humans
  • Kidney / immunology
  • Longitudinal Studies
  • Lupus Erythematosus, Systemic / blood
  • Lupus Erythematosus, Systemic / immunology*
  • Lupus Nephritis / blood
  • Lupus Nephritis / immunology
  • Male
  • Prospective Studies
  • Receptors, Complement 3b / blood
  • Receptors, Complement 3b / immunology*


  • Complement C3
  • Complement C4
  • Receptors, Complement 3b