Guidelines for assessing immunocompetency in clinical trials for autoimmune diseases

Is immunology doing well? A look at 100 immune-mediated inflammatory diseases for 100 years of the Journal

It is now 60 years since Ian Mackay and Macfarlane Burnet published their seminal text "The Autoimmune Diseases" in which they examined the full scope of human inflammatory pathology as a manifestation of the underlying structure and function of the immune system. Here I revisit this approach to ask to what extent has the promise of Mackay and Burnet's work been exploited in clinical medicine as currently practiced. In other words, is immunology doing well? Despite spectacular headline contributions of immunology in clinical medicine, I present evidence suggesting a performance ceiling in our capacity to answer the relatively straightforward questions that patients frequently ask about their own diseases and find that this ceiling exists across almost all of the 100 immune-mediated inflammatory diseases examined. I propose that these questions are difficult, not so much because the immune system is overwhelmingly complex but rather that we have more to learn about the relatively simple agents and rules that may underpin self-organizing complex interacting systems as revealed in studies from other disciplines. The way that the immune system has evolved to exploit the ancient machinery determining three independent cell fate timers as described in this Journal would be a great place to start to decode the self-organizing principles that underpin the emergent pathology that we observe in the clinic.

A novel assay to measure B cell responses to keyhole limpet haemocyanin vaccination in healthy volunteers and subjects with systemic lupus erythematosus

The aim of the study was to characterize performance of a complementary set of assays to measure antigen-specific immune responses in subjects immunized with a neoantigen. Healthy volunteers (HV) (n = 8) and patients with systemic lupus erythematosus (SLE) (n = 6) were immunized with keyhole limpet haemocyanin (KLH) on days 1 and 29. Serum antibodies were detected using a flow cytometric bead array (CBA) that multiplexed the KLH response alongside pre-existing anti-tetanus antibodies. Peripheral blood mononuclear cells were studied by B cell ELISPOT. These assays were built upon precedent assay development in cynomolgus monkeys, which pointed towards their utility in humans. Primary anti-KLH IgG responses rose to a mean of 65-93-fold above baseline for HV and SLE patients, respectively, and secondary responses rose to a mean of 260-170-fold above baseline. High levels of anti-tetanus IgG were detected in pre-immunization samples and their levels did not change over the course of study. Anti-KLH IgG1-4 subclasses were characterized by a predominant IgG1 response, with no significant differences in subclass magnitude or distribution between HV and SLE subjects. Anti-KLH IgM levels were detectable, although the overall response was lower. IgM was not detected in two SLE subjects whodid generate an IgG response. All subjects responded to KLH by B cell ELISPOT, with no significant differences observed between HV and SLE subjects. The CBA and B cell ELISPOT assays reliably measured anti-KLH B cell responses, supporting use of this approach and these assays to assess the pharmacodynamic and potential safety impact of marketed/investigational immune-therapeutics.

Therapeutic targeting of the IL-12/23 pathways: generation and characterization of ustekinumab

Preclinical and clinical studies conducted in the mid-1990s reported strong association and causality between the T-cell helper (T(H)) 1 inductor cytokine interleukin (IL)-12 and numerous immune-mediated disorders, which spurred the development of therapeutic agents targeting IL-12 function. One of the first to enter the clinic, ustekinumab, is a human monoclonal antibody (mAb) that binds to the p40 subunit of IL-12. Subsequent to the generation of ustekinumab, it was discovered that IL-23 also contains the p40 subunit. Thus, although ustekinumab was designed to target IL-12, it also modulates IL-23, a cytokine important to the development and/or maintenance of T(H)17 cells. Clinical observations established that IL-12/23p40 is integral to the pathologies of psoriasis, psoriatic arthritis and Crohn's disease. The molecular and cellular evaluations conducted in ustekinumab clinical programs have provided numerous insights into the pathologic processes of these disorders, illustrating how a novel molecular entity can contribute to our understanding of disease. The individual contributions of these cytokines to specific pathologies require investigation and clinical evaluation of the role of IL-12- and IL-23-specific inhibitors.

Immune Responses to pneumococcal vaccines in children and adults: Rationale for age-specific vaccination

Streptococcus pneumoniae is a significant human pathogen and currently available pneumococcal vaccines are designed to elicit anti-capsule antibodies. The 23-valent polysaccharide vaccine has been used in older adults for many years whereas 7-, 10-, and 13-valent pneumococcal conjugate vaccines have only been used commonly for young children in the last decade. In addition to their high protective efficacy among children, the use of conjugate vaccines in young children has had a number of additional effects, including production of a serotype shift and providing new herd immunity to adults. The immunogenicity of both of these types of vaccines can be determined by using an ELISA assay to measure antibody levels or an opsonophagocytosis assay to assess opsonic function. As these assays have improved over time, awareness of the analytical limitations of older studies has grown. While the 23-valent vaccine is effective among young adults, it is less effective among elderly adults. Aging-associated ineffectiveness may be due to aging-dependent changes in the antibody repertoire and/or a reduction in IgM antibody production associated with aging-dependent changes in B cell subpopulations. The immunologic basis of aging-associated immune defects thus remains an active area of research.

Update on the use of rituximab for intractable rheumatoid arthritis

It has been 3 years since rituximab, a mouse x human chimeric anti-CD20 monoclonal antibody that selectively depleted B cells, was approved by the FDA for the treatment of moderate to severe rheumatoid arthritis (RA) with an inadequate response to anti-TNF therapies. Since approval rituximab has become a part of standard treatment, and additional data have become available on long-term efficacy and safety both from clinical trials and from post-marketing surveillance. In open long-term follow-up from clinical trials, patients treated with multiple courses of rituximab continued to respond in terms of signs and symptoms, and damage assessed radiographically was significantly inhibited. Moreover, the rate of serious infectious events was not increased as the number of courses increased. However, because of case reports of progressive multifocal leukoencephalopathy in patients treated with rituximab for non-malignant conditions, a black box warning has been added. Studies on the immunologic correlates of response to rituximab treatment including B cell subsets in peripheral blood and synovial biopsies are providing clues into how rituximab works for autoimmune disease. However, at this time we are not able to explain why some patients do not respond and cannot predict who will respond. Future challenges for the further development of rituximab for intractable RA will be discussed.

Monitoring peripheral blood CD4+ adenosine triphosphate activity in a liver transplant cohort: insight into the interplay between hepatitis C virus infection and cellular immunity

Peripheral blood CD4+ adenosine triphosphate [ATP (ng/mL)] release [ImmuKnow Immune Cell Function Assay (ATP)] correlates to immunoreactivity. We hypothesized that ATP levels could provide insight into hepatitis C virus (HCV) infection and recurrent liver disease in liver transplantation (LT). We studied our center's LT cohort, in which ATP levels had been measured off protocol from February 2005 through July 2006. Of the 280 LTs performed since 1993, 114 (58.2%) fit the selection criteria, with a mean age of 49 +/- 10 years. LT (alone/combination) indications included HCV (58%), alcoholic liver disease (41%), hepatocellular carcinoma (16%), and other (33%). Four hundred seventy-seven ATP levels were obtained: 3 (1-17) per patient 25 months (4 days to 19 years) from the time from transplantation. Final diagnoses were normal allograft function (n = 166, 35%), recurrent disease (n = 199, 42%), septic event (n = 34, 7%), other (n = 51, 11%), and undetermined (n = 27, 6%). Two hundred eighty-one ATP levels were obtained [3 (1-18) per patient] in 66 HCV(+) patients. Forty-five (68%) developed biopsy-proven recurrent liver disease [188/281 (67%) ATP levels]. The median ATP level (ng/mL) was 162 (1-761); it was lower in HCV(+) patients (151 +/- 109) versus HCV(-) patients (211 +/- 139; P < 0.0001). ATP ranges in HCV(+) patients were stable from the time from transplantation. In HCV(-) patients, ATP ranges were initially high and eventually decreased to HCV(+) levels (P = 0.01). Immunosuppressant levels were low in 62% of HCV(-) patients versus 38% of HCV(+) patients (P = 0.04). In HCV(+) patients, ATP was lower in disease recurrence (139 +/- 97) versus none (181 +/- 141; P = 0.01) with similar immunosuppression, and ATP decreased with grade (P = 0.05) but not stage. Time from transplantation, aspartate aminotransferase/alanine aminotransferase >1, and low ATP were independently associated with recurrent HCV. In conclusion, after LT, global cellular immune function appears depressed at baseline in HCV(+) patients versus HCV(-) patients and more so in HCV(+) recurrent disease.