Trial of Rituximab and Mycophenolate Mofetil Without Oral Steroids for Lupus Nephritis

1. Adults aged 18-75 years old and children aged 12-17 years old. 2. Active lupus nephritis, as defined by kidney biopsy within prior 8 weeks assessed by the International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification: 1. class III (A or A/C) with active lesions in at least 20% of the viable glomeruli, or 2. class IV-S (A or A/C) with active lesions in at least 20% of the viable glomeruli, or 3. class IV-G (A or A/C) with active lesions in at least 20% of the viable glomeruli and / or 4. class V and 5. urine protein-to-creatinine ratio equal to or greater than 100mg/mmol (\>1mg/mg ) at randomisation or at any time within 28 days before randomisation 3. No contraindications to the use of IV methyl prednisolone, MMF, oral steroids or rituximab or any other required medications such as antipyretics, antihistamines 4. Ability to provide informed consent 5. As MMF is teratogenic and on basis of advice from NHS England (The updated recommendations (https://www.gov.uk/drug-safety-update/mycophenolate-mofetil-mycophenolic-acid-new-pregnancy-prevention-advice-for-women-and-men) for patients whilst on MMF and after stopping are: * Women who have child bearing potential should be willing to use 2 forms of effective contraception during treatment and for 6 weeks after stopping treatment * Men (including those who have had a vasectomy) should be willing to use condoms during treatment and for at least 90 days after stopping treatment. This advice is a precautionary measure due to the genotoxicity of these products * Female partners of male patients treated with mycophenolate mofetil should use highly effective contraception during treatment and for 90 days after the last dose Exclusion criteria: 1. Obsolescence of \>50% of the glomeruli or tubulointerstitial scarring of \>50% or cellular crescents in \>50% of the glomeruli 2. Severe "critical" SLE flare defined as: 1. BILAG 2004 A flare in CNS system 2. or any SLE manifestation requiring more immunosuppression than allowed within the protocol in the physician's opinion 3. Pregnant or lactating. Woman who have child bearing potential must have two negative pregnancy test results with a sensitivity of ≥ 25 mIU/mL: one from a serum pregnancy test at day -8 to day -10 of screening and another from a urine pregnancy test at day 1 prior to randomisation. If the timeline is shortened because of clinical urgency, then there must be a negative serum pregnancy test with a sensitivity of ≥ 25 mIU/mL within 1-2 days before study start 4. Patients not willing for their GP to be informed of their participation in this study 5. Patients should not be on or require maintenance steroids and should not have had more than 12 weeks of steroids in the period immediately preceding recruitment irrespective of dose 6. Patients that had received more than 2.0g of IV methyl prednisolone in the previous 4 weeks 7. Prior use within 12 months of screening visit of therapeutic monoclonal antibody, or B or T cell modulating 'biologic' use 8. Prior use within 6 months of the screening visit of Intravenous immunoglobulin / plasma exchange OR Cyclophosphamide 9. Active infections, including but not limited to the human immunodeficiency virus (HIV), and hepatitis B (including prior infection as judged by positive Hepatitis B core antibody) or Hepatitis C or tuberculosis 10. Receipt of a live-attenuated vaccine within 3 months of study enrolment 11. In the investigator's opinion, patients that are at high risk for infection (including but not limited to indwelling catheter, dysphagia with aspiration, decubitus ulcer, history of prior aspiration pneumonia or recurrent severe urinary tract infection) 12. Prior history of invasive fungal infections 13. History of any cancer 14. In female patients, known history of cervical dysplasia CIN Grade III cervical high risk human papillomavirus or abnormal cervical cytology other than abnormal squamous cells of undetermined significance (ASCUS) within the past 3 years. The patient will be eligible after the condition has resolved (e.g., follow-up HPV test is negative or cervical abnormality has been effectively treated \>1 year ago) 15. Any concomitant medical condition or abnormal blood results that in the investigator's opinion, or after discussion with the CI, places the participant at risk by participating in this study. 16. Comorbidities requiring systemic corticosteroid therapy. 17. Current substance abuse.