An update on clinical immunology, immune mechanisms and deficiency diseases

Abstract

29th Annual Jackson Hole, Wyoming, Update in Clinical Immunology, Microbiology and Infectious Diseases

Salt Lake city, UT, USA, 9–13 July 2012

The 29th Annual Jackson Hole, Wyoming, Update in Clinical Immunology, Microbiology and Infectious Diseases was held from 9 to 13 July 2012. This postgraduate, continuing medical education course of the University of Utah’s Department of Pathology (UT, USA) is designed for laboratorians, clinical pathologists, pathologists, clinicians, clinical immunology and infectious disease specialists and medical technologists, as well as residents and fellows training in immunology, microbiology or infectious diseases.

Keywords::

• hypogammaglobulinemia
• immunodeficiency
• immunologic assay
• inflammatory bowel disease
• mycobacterial infections
• neutrophils
• plague
• sickle cell disease

Harry R Hill, Professor of Pathology, Pediatrics and Medicine at the University of Utah (UT, USA), and one of the course directors reviewed the clinical and laboratory features of Job syndrome of Hyper IgE and Recurrent Infections including the syndrome’s original description by Davis, Schaller and Wedgwood. These patients suffer severe, recurrent staphylococcal abscesses and pneumonias, often with pneumatocoele development, mucocutaneous candida infections along with severe eczema and bone fractures, after relatively minor trauma. They also have characteristic facial features, with broad nasal bridges and nasal alae, frontal bossing, prominent lower lips and doughy consistency of the skin of the face, likely from repeated episodes of eczema. Early papers suggested an altered inflammatory response in these patients and, more recently, most patients with the autosomal dominant form of the disease, with the characteristics described above, have been found to have mutations in the STAT3 gene, which is critical in inflammation and the development of Th17 cells important in bacterial and fungal immunity. He then described a rapid, high-resolution melting, scanning assay that is capable of detecting mutations in this gene in as little as 8 h and its application to a series of patients with Job syndrome of hyper IgE and recurrent infection [1]. He pointed out both familial cases with three to four affected members in a single family as well as spontaneous new mutations with Job syndrome in one individual in a family with 13 unaffected siblings, along with the unaffected mother and father.

Paul G Quie, Regents Professor Emeritus of Pediatrics and Pathology, and Co-Director of the International Medical Education and Research Program at the University of Minnesota (MN, USA) spoke on, ‘The Neutrophil: A Two-Edged Sword’. Quie indicated that approximately 100 billion neutrophils, which contribute to innate and adaptive immunity, are produced by the human body each day. These cells circulate in the blood stream, diapedese into the tissues and become first responders to any microbial invasion. Neutrophils have an unusual membrane enzyme in NADPH oxidase, which produces reactive oxygen radicals that can cause rapid killing of microbes. In addition, they contain granules, which contain enzymes and proteases including defensins, which are also microbicidal. The factors responsible for killing microbes intracellularly can have deleterious effects when released into the tissues that play a role in the pathogenesis of vasculitis and other chronic inflammatory diseases [2]. The neutrophils may also release a variety of different cytokines. Therapeutic agents are being developed that target the neutrophil and its ability to produce such disorders.

Mark Eberle, of the Central Oregon Community College (OR, USA), presented a fascinating view of the ‘History of Plague’ including early attempts at promoting host resistance and preventing plague [3]. He entered the lecture hall in a plague health worker’s suit with glazed eye holes and an extended beak containing aromatic spices as well as slick wax fabric, all designed to counter the miasmas thought to cause the plague. This included a stick to keep patients at a distance to prevent the spread of the miasmas. Interestingly, it was noted by a public health worker in 1657 that the wax robe used by workers in a plague treatment house was good only to protect one from the fleas, which apparently could not nest in it. Ironically, the role of the fleas as vectors of the plague was a mystery until 1900. This was a fascinating lecture and pointed out the development of our understanding of the transmission of this not uncommon infectious disease, which still occurs in localized outbreaks even in the USA in squirrels and other rodents.

Anne Tebo of the Department of Pathology at the University of Utah and Director of the Autoimmune Immunology Laboratory at ARUP Laboratories (UT, USA) spoke on ‘Laboratory Evaluation of Inflammatory Bowel Disease – When Less is More’. She highlighted the controversies regarding the use of serologic, genetic and inflammatory markers in the evaluation of inflammatory bowel disease (IBD).

There is considerable clinical evidence that the more readily available and cost-effective anti-Saccharomyces cerrevisae IgG and IgA, as well as the atypical perinuclear, antineutrophil cytoplasmic antibodies tests remain the relevant diagnostic tools in the assessment of IBD [4]. With the identification of more than 100 IBD risk loci and only 25% of genetic variance explained in IBD, Tebo contended this type of testing would be clinically appropriate only if implemented in an integrated approach. Overall, she made a case for an incremental approach to the laboratory evaluation of IBD, which would also save money in these all too common, gastrointestinal disorders.

Frederick A Meier, Professor of Pathology and Director of Regional Pathology Services at the Henry Ford Hospital (MI, USA) subsequently spoke on the immune response in sickle cell disease patients. He indicated that oxidative metabolites and catalase along with superoxide dismutase and dysregulation of the nitric oxide pathway result in endothelial cell damage secondary to oxidative stress. Hemolyzed red blood cell fragments and platelet activation, generated during the hemolytic crises, further occludes small vessels and amplifies endothelial injury in these patients. This, along with PAF receptor alterations, contribute to the endothelial damage, which impairs splenic phagocytosis and shortens the survival of, particularly, IgM memory B cells [5]. Red cell fragments from hemolysis clog the reticular endothelial system and this along with the IgM deficiency often contribute to disseminated pneumococcal disease. This suggests a need for immunization of patients with sickle cell disease using the Streptococcus pneumonia vaccine.

Hill, who sees adult and pediatric patients with primary immune deficiency diseases at the University of Utah, then discussed the presentation, laboratory diagnosis, and molecular basis of common variable immune deficiency disease (CVID), the most common primary immune deficiency with an instance of somewhere between one in 25,000 and one in 50,000 [6]. He described several patients who presented with severe, invasive, bacterial infections or chronic pulmonary infections, and gastrointestinal complications, including, chronic diarrhea and giardiasis. He went over the laboratory tests used in diagnosing CVID, including nephelometric determinations of serum levels of IgG, IgM, IgA and IgG subclasses, as well as B-cell and T-cell quantitation and characterization using flow cytometry and immunofixation electrophoresis to rule out monoclonal proteins, which can also depress immunoglobulins. Subsequently, Hill described the known molecular causes of CVID, which only make up approximately 20% of cases including abnormalities in CD19, CD20, CD21, CD81, TACI, BAFF receptor and ICOS, and pointed out the families in which he and Attila Kumánovics and Karl Voelkerding have been employing comparative genomic hybridization arrays, to detect deletions and duplications, and next generation sequencing to find new molecular causes of CVID.

Attila Kumánovics, Assistant Professor in the Department of Pathology at the University of Utah, and Director of the Molecular Immunology Laboratory at ARUP Laboratories, then discussed the genetics of other primary immune deficiencies. He pointed out that there are at least 150 such primary immune deficiencies described in the literature that result from thousands of mutations in well over 200 different genes [7]. He indicated that using genomic microarrays and massively parallel, next-generation sequencing, we are discovering additional genetic abnormalities causing these disorders. He then went into detail about susceptibility to mycobacterial disease (MSMD) and mucocutaneous candidiasis, which can result from mutations in a number of genes [8,9]. All the known causes of MSMD and CMC result in decreased critical cytokine mediated immunity against mycobacteria and candida, respectively. MSMD can be inherited as autosomal dominant, autosomal recessive, or in an X-linked manner. Seven genes are known with MSMD mutations [8]. These genes are involved in the signaling of IFN-γ (IFNGR1, IFNGR2, STAT1) and IL-12 (IL12B, IL12RB1, TYK2) or regulate the IL12 and IFN-γ signaling pathways (IKBKG/NEMO). CMC can be inherited as autosomal dominant or autosomal recessive manner. Genes with mutations causing CMC lead to decreased IL-17 and/or IL-22 immunity [9]. CMC genes encode receptors that recognize fungal organisms (DECTIN1), participate in the signaling pathway following the pathogen recognition (CARD9), required for Th17 cell differentiation (STAT3, STAT1, DOCK8), encode IL17 (IL17F) or IL17 receptor (IL17RA). Mutations in AIRE (autoimmune regulator), result in autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy syndrome (APECED), which includes the production of neutralizing antibodies against IL17 and IL22. Last, he described the use of T-cell excision circles produced during T-cell maturation in newborn screening for severe combined immunodeficiency [10].

Thomas B Martins, Senior Scientist in the ARUP Institute for Clinical and Experimental Pathology, then discussed a new, functional assay for detecting neutralizing antibody to IFN-β in patients with multiple sclerosis (MS). Patients with MS therapy-induced neutralizing antibodies (NAbs) to IFN-β have reduced responses to IFN-β treatment, resulting in higher relapse rates, increased MRI activity and a higher risk of disease progression. A functional assay was employed for both screening and titering of IFN-β NAbs utilizing a human cell line transfected with a luciferase reporter gene responsive to IFN-β. This assay demonstrated 100% sensitivity and specificity compared with the traditional viral cytopathic effect assay. Additionally, 183 MS patients undergoing therapy with IFN-β were tested in the reporter gene assay. The IFN-β reporter gene assay showed excellent correlation with the well-established cytopathic effect assay offering clear advantages. The use of this functional assay should be a valuable tool for detecting and monitoring the presence of NAbs in IFN-β treated MS patients.

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.