Abstract | OBJECTIVE: To determine whether opsonization of Streptococcus pneumoniae with C3b/ iC3b is impaired in serum from patients with SLE. METHODS: The ability of serum samples from 30 patients with SLE, 20 with non-SLE rheumatic diseases (RA, PsA, AS, SS) and 20 healthy controls to opsonize S. pneumoniae (strains D39 and Io11697) with C3b/ iC3b was assessed using a standardized FACS technique and a FACSCalibur flow cytometer. Results were compared among the three groups using analysis of variance, followed by pairwise comparisons among groups using the Mann-Whitney U-test. RESULTS: The proportion of bacteria positive for C3b/ iC3b was significantly lower in serum from patients with SLE (strain D39: 60.3% +/- s.e.m. 2.87, strain Io11697: 55.3% +/- 3.8) compared with healthy controls (strain D39: 70.6% +/- 2.0, P = 0.01; strain Io11697: 67.8% +/- 2.6; P = 0.05) and non-SLE rheumatic controls (strain D39: 69.8% +/- 3.1; P = 0.03). For the patients with SLE, there was no association between C3b/ iC3b deposition and serum complement levels or measurable classical pathway activity. C3b/ iC3b deposition on S. pneumoniae was significantly lower in serum from SLE patients with a past history of pneumonia (n = 3) compared with those without (n = 27; P = 0.03). CONCLUSIONS: Opsonization of S. pneumoniae with C3b/ iC3b was significantly reduced in serum from patients with SLE compared with non-SLE rheumatic disease and healthy controls. Failure to appropriately activate the immune system via complement may contribute to the increased susceptibility of SLE subjects to infections, and may correlate with a risk of pneumonia in a subgroup of SLE patients.
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Authors | Fiona Goldblatt, Jose Yuste, David A Isenberg, Anisur Rahman, Jeremy Brown |
Journal | Rheumatology (Oxford, England)
(Rheumatology (Oxford))
Vol. 48
Issue 12
Pg. 1498-501
(Dec 2009)
ISSN: 1462-0332 [Electronic] England |
PMID | 19797312
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
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Topics |
- Adult
- Aged
- Complement C3b
(metabolism)
- Complement Pathway, Classical
(immunology)
- Humans
- Immune Tolerance
- Lupus Erythematosus, Systemic
(complications, immunology)
- Middle Aged
- Opportunistic Infections
(complications, immunology)
- Phagocytosis
(immunology)
- Pneumococcal Infections
(complications, immunology)
- Streptococcus pneumoniae
(immunology)
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