SLE with C1q deficiency treated with fresh frozen plasma: a 10-year experience SIR, We present the case of a 24-year-old female of Pakistani origin with an SLE-like illness secondary to complete C1q deficiency, treated successfully with fresh frozen plasma (FFP) therapy since the age of 15 years. Her clinical presentation has been previously reported [1]. She presented at the age of 6 years with cutaneous lupus and developed seizures secondary to cerebral lupus at the age of 11 years. Despite treating with prednisolone (15mg/day) and AZA (75mg/day), her disease remained active at the age of 15 years. Clinical features included fatigue, fever, arthralgia, mucosal ulceration, headache, malar rash, weight loss and amenorrhea. She had also developed fungal nail infections and recurrent urinary and respiratory bacterial infections. Examination findings included Cushingoid appearance, malar rash, alopecia, oral ulcers, arthralgia and fever. ANAs were positive at 1: 640 titre (speckled pattern). Antibodies against dsDNA and ENAs were absent. Complement C3 was 1.28 (0.7–1.7) g/l and C4 0.64 (0.16–0.54) g/l. Classical complement haemolytic activity (CH100) was absent and serum C1q protein was not detectable using ELISA and Ouchterlony assays. We defined the genetic abnormality as a homozygous single nucleotide deletion within the C1qC gene (c. 166delG) resulting in a reading frame shift and generation of a premature stop codon (p. Gly55Glyfs83X). Homozygous C1q deficiency predisposes to an SLE-like illness in the majority of cases [2]. Therapy of SLE associated with complement deficiency comprises (i) standard therapeutic regimens used in complementsufficient lupus patients and (ii) specific strategies that aim to replace the missing protein. The major source of C1q is from bone marrow-derived cells and therefore bone marrow transplantation could theoretically be curative. To our knowledge, this has not been attempted in humans, but has rectified autoimmunity in C1q-deficient mice [3]. No suitable HLA-matched sibling donor was available and the risk–benefit analysis associated with matched unrelated donor transplantation was considered unfavourable. We therefore attempted interval replacement of C1q through the use of infusions of detergent-treated FFP (Octaplas). The C1q level in Octaplas was 157 μg/ml, representing 84% of the control sera level (187 μg/ml). After a single intravenous infusion of 10ml/kg Octaplas, serum C1q was detectable in the patient’s sera with levels peaking 2h after the infusion (Fig. 1). CH100 returned to normal at 12 and 24h post-infusion, demonstrating that the C1q within Octaplas was sufficient to restore complement haemolytic activity. Similar time courses have been reported previously [4, 5]. We therefore proceeded with an Octaplas infusion regimen that consisted of four infusions at weekly intervals followed by six infusions at fortnightly intervals. Thereafter, infusions were continued at 3 weekly cycles. The patient demonstrated a dramatic improvement during the infusion regime. By 6 months, her symptoms had fully resolved and the dose of prednisolone was reduced to 5 mg/day. Subsequently, it was possible to reduce her infusion frequency to 4 weekly cycles. Attempts to increase the intervals to 5-week cycles resulted in recurrence of lethargy and mouth ulcers in the week leading up to the next infusion cycle. She has continued to receive monthly Octaplas infusions over the last decade during which she has not required significant increase in her prednisolone therapy or additional immunosuppression. She remains on AZA (75mg/day) and prednisolone (5mg/day). Importantly, the therapy has …