Patients and controls
Patients who were treated with alemtuzumab (CAMPATH-1H) for RA between 1991 and 1994 were identified from the study database. Cumulative alemtuzumab doses were documented for each individual; of note, these doses were comparatively lower than those seen with other more widely used biological therapies. Mortality data for this cohort were collected from 9 March 2006 (end date of our previous study) until 1 January 2015 from the National Health Service Central Registry. Morbidity information was collected on all living and consenting patients by either interview or review of clinical case notes. Special attention was given to episodes of severe infection, cancers and autoimmunity. Age and sex matched patients with RA of similar disease duration, who had not received alemtuzumab, were identified locally in Cambridge, UK. Research was performed in compliance with the Declaration of Helsinki and the International Conference on Harmonisation Good Clinical Practice. Ethical approval for the study was provided by Scotland A Research Ethics Committee (REC 10/MRE00/68).
Clinical parameters
Clinical and serological parameters were obtained from all patients attending interview. Markers of disease activity included erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), tender joint count (TJC), swollen joint count (SJC), patient-reported visual analogue scale (VAS), disease activity score in 28 joints (DAS-28)-ESR and patient health assessment questionnaire (HAQ). Anti-cyclic citrullinated peptide (anti-CCP) antibody and rheumatoid factor (RF) IgM titres and serum immunoglobulins (IgG, IgA, IgM), serum electrophoresis and lymphocyte count were analysed in the clinical laboratories of Addenbrooke’s Hospital, Cambridge, according to routine clinical practice and national standards.
Vaccine responses
Subjects were offered vaccination with: 0.5 ml influenza vaccine (Pfizer Ltd, Sandwich, UK), a split, inactivated influenza vaccine containing antigens equivalent to A/California/7/2009 (H1N1) pdm09-derived strain (NYMC X-181), A/Victoria/361/2011 (H3N2)-derived strain (IVR-165) and B/Wisconsin/1/2010–like strain (NYMC BX-39) derived from B/Hubei- B/ Wujiagang/158/2009; 0.5 ml Pneumovax II (Sanofi Pasteur MSD Ltd, Maidenhead, UK), a vaccine containing 25 μg of each of the following 23 pneumococcal polysaccharide serotypes: 1, 2, 3, 4, 5, 6B, 7 F, 8, 9 N, 9 V, 10A, 11A, 12 F, 14, 15B, 17 F, 18C, 19 F, 19A, 20, 22 F, 23 F, 33 F; and 0.5 ml Revaxis (Sanofi Pasteur MSD Ltd, Maidenhead, UK) containing 2 IU purified diphtheria toxoid, 20 IU purified tetanus toxoid and inactivated poliomyelitis virus types 1-3.
Vaccine responses were assessed in serum obtained at baseline and 4 weeks post vaccination. Analyses were performed at the Respiratory Virus Unit, Health Protection Agency, London UK (influenza), the Vaccine Evaluation Unit, Public Health England, Manchester (pneumococcus, diphtheria and tetanus) and Public Heath England, Enteric Virus Unit, London (poliovirus). Satisfactory response to pneumococcal vaccine was defined as a doubling (or greater) in antibody concentrations to 6 or more of 12 pneumococcal serotypes (1, 3, 4, 5, 6B, 7 F, 9 V, 14, 19A, 19 F, 23 F and 18C). Tetanus and diphtheria seroprotection was achieved when IgG titres were >1.0 IU/ml. These were booster vaccines and some patients had residual seroprotection pre-administration. These patients were excluded from subsequent seroconversion analysis, which was defined as when vaccination achieved new seroprotection.
For poliovirus, neutralizing antibodies were quantified, with seroprotection with titres ≥1:8 and seroconversion following ≥4 fold increase in titres. For influenza, HAI assays were performed, with seroprotection when titres were >1:40 and seroconversion when post-vaccination titre increased by ≥3 fold. The seroconversion factor was the mean rise in geometric mean titres (GMT) post vaccination (recommended ≥2) and seroconversion rate was the percentage of vaccinees with an increase in haemagglutination inhibition (HAI) titre ≥4 fold following vaccination (recommended >30%). Some patients had annual influenza vaccines prior to recruitment into the study. These individuals were not vaccinated again but anti-influenza titres were measured in baseline serum. Any adverse effects were collected 4 weeks post vaccination.
Serum cytokines
At the initial visit cytokines (IL-15, IL-7, IFN-γ, IL-10, IL-12, IL-13, IL1-beta, IL-2, IL-4, IL-6, IL-8, TNF-alpha and granulocyte macrophage colony stimulating factor (GM-CSF)) were measured in serum by MSD technology (Meso Scale Discovery, MD, USA) as per established protocol.
Immunophenotyping
Peripheral blood lymphocytes were immunophenotyped by multicolour flow cytometry using the following antibodies: anti-CD3 Pacific Blue, anti-CD56 FITC, Anti-CD27 PE, anti-CD28 APC, anti-CD1d PE, anti-CD19 APC, anti-CD27 V450, anti-CD38 PerCP-Cy5.5 (all from BD Biosciences, San Jose, CA, USA) and anti-CD45RA PerCP-Cy5.5, anti-CD62L PE-Cy7, anti-CD5 PE-Cy7, anti-CD24 APC-eFluor 780 and anti-CD4 APC-eFluor 780 (from eBioscience, Inc. San Diego, CA, USA). Staining was performed on whole blood using BD FACS Lysing Solution (BD Biosciences) as per the manufacturer’s instructions. A minimum of 250,000 events were acquired for T cell panels and 500,000 events for B cell panels to ensure adequate capture of rare populations. Subsequent detailed analysis of lymphocyte sub-populations was performed on the gated lymphocyte population using FlowJo (Treestar, Inc., OR, USA). Absolute counts for the different lymphocyte populations were calculated per litre of blood, based on haematology laboratory reported total lymphocyte count.
Statistical analysis
Statistical analysis was performed using the Mann-Whitney U test, Wilcoxon signed rank test and linear regression using Prism 4.0 (GraphPad Software, Inc., La Jolla, CA, USA). P values <0.05 were considered significant.