Complement Receptor Type 1 Suppresses Human B Cell Functions in SLE Patients

Figure 1

Impact of CR1 clustering on BCR-induced proliferation of B cells. 2 × 10⁵ B cells isolated from healthy donors (a) or active SLE patients (b) were activated with 5 μg/mL F(ab’)₂ fragment of anti-human IgG+M+A Ab in the presence or absence of different concentrations of heat-aggregated C3, surface coated C3b, or the CR1-specific antibody (To5) clustered by anti-mouse IgG. As control, cells were cultured in medium or with an isotype-matched control mouse IgG. Cells were harvested after pulsing with 1 μCi/well H³-thymidine for the last 16 hours of culture. (a and b) Data shown are mean ± SD cpm of triplicate cultures and representative of five independent experiments with similar results is shown. (c) Results showing percent of inhibition mediated by aggregated C3, C3b, or the anti-CR1 Ab (To5) are mean % of inhibition ± SEM of five independent experiments and correlated with the CR1-agonist untreated sample (see Section 2, Permutation-test; and ).

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