The immunoglobulinopathies: from physiopathology to diagnosis

Subretinal autofluorescent deposits: A review and proposal for clinical classification

Subretinal autofluorescent deposits (SADs) may be found in the posterior pole, associated with very various conditions. These disorders usually present a typical pattern of autofluorescent lesions seen on short-wavelength fundus autofluorescence. We describe SADs according to their putative pathophysiological origin and also according to their clinical pattern, i.e., number, shape, and usual location. Five main putative pathophysiological origins of SADs were identified in disorders associated with an intrinsic impairment of phagocytosis and protein transportation, with excess of retinal pigment epithelium phagocytic capacity, with direct or indirect retinal pigment epithelium injury, and/or disorders associated with long-standing serous retinal detachment with mechanical separation between the retinal pigment epithelium and the photoreceptor outer segments. Clinically, however, they could be classified into eight subclasses of SADs, as observed on fundus autofluorescence as follows: single vitelliform macular lesion, multiple roundish or vitelliform lesions, multiple peripapillary lesions, flecked lesions, leopard-spot lesions, macular patterned lesions, patterned lesions located in the same area as the causal disorder, or nonpatterned lesions. Thus, if multimodal imaging may be required to diagnose the cause of SADs, the proposed classification based on noninvasive, widely available short-wavelength fundus autofluorescence could guide clinicians in making their diagnosis decision tree before considering the use of more invasive tools.

Polyacrylamide gel photopatterning enables automated protein immunoblotting in a two-dimensional microdevice

We demonstrate a two-dimensional microfluidic architecture that integrates polyacrylamide gel electrophoresis (PAGE) with immunoblotting in a fully automated format. This assay is designed to overcome performance limitations of conventional slab-gel immunoblotting, including multiple manual interventions, low-throughput transfer and blotting, and substantial consumption of reagents and sample. To unify PAGE with blotting in one device, this microfluidic approach makes use of high-resolution regional photopatterning of multiple polyacrylamide gel elements, and automated electrophoretic transport. A complete native immunoblot of free prostate specific antigen from human seminal fluid is demonstrated in less than 5 min. Further, the characterization of post-PAGE electrophoretic transfer showed high efficiency and minimal sample dispersion.

A better understanding of molecular mechanisms underlying human disease

This review summarises and discusses the degree to which proteomics is contributing to medical care, providing examples and signspots for future directions. Why do genomic approaches provide a limited view of gene expression? Because of the multifactorial nature of many diseases, proteomics enables us to understand the molecular basis of disease, not only at the organism, whole-cell or tissue levels, but also in subcellular structures, protein complexes and biological fluids. The application of proteomics in medicine is expected to have a major impact by providing an integrated view of individual disease processes. This review describes several proteomic platforms and examines the role of proteomics as a tool for clinical biomarker discovery, the identification of prognostic and earlier diagnostic markers, their use in monitoring the effects of drug treatments and eventually find more efficient and safer therapeutics for a wide range of pathologies.

Proteomics of Blood-Based Therapeutics

Blood-based therapeutics are cellular or plasma components derived from human blood. Their production requires appropriate selection and treatment of the donor and processing of cells or plasma proteins. In contrast to clearly defined, chemically synthesized drugs, blood-derived therapeutics are highly complex mixtures of plasma proteins or even more complex cells. Pathogen transmission by the product as well as changes in the integrity of blood constituents resulting in loss of function or immune modulation are currently important issues in transfusion medicine. Protein modifications can occur during various steps of the production process, such as acquisition, enrichment of separate components (e.g. coagulation factors, cell populations), virus inactivation, conservation, and storage. Contemporary proteomic strategies allow a comprehensive assessment of protein modifications with high coverage, offer capabilities for qualitative and even quantitative analysis, and for high-throughput protein identification. Traditionally, proteomics approaches predominantly relied on two-dimensional gel electrophoresis (2-DE). Even if 2-DE is still state of the art, it has inherent limitations that are mainly based on the physicochemical properties of the proteins analyzed; for example, proteins with extremes in molecular mass and hydrophobicity (most membrane proteins) are difficult to assess by 2-DE. These limitations have fostered the development of mass spectrometry centered on non-gel-based separation approaches, which have proven to be highly successful and are thus complementing and even partially replacing 2-DE-based approaches. Although blood constituents have been extensively analyzed by proteomics, this technology has not been widely applied to assess or even improve blood-derived therapeutics, or to monitor the production processes. As proteomic technologies have the capacity to provide comprehensive information about changes occurring during processing and storage of blood products, proteomics can potentially guide improvement of pathogen inactivation procedures and engineering of stem cells, and may also allow a better understanding of factors influencing the immunogenicity of blood-derived therapeutics. An important development in proteomics is the reduction of inter-assay variability. This now allows the screening of samples taken from the same product over time or before and after processing. Optimized preparation procedures and storage conditions will reduce the risk of protein alterations, which in turn may contribute to better recovery, reduced exposure to allogeneic proteins, and increased transfusion safety.

Clinical proteomics: study of a cryogel

Cryoproteins are proteins precipitating at low temperature. Usually, the precipitate contains immunoglobulins (Igs), and are therefore called cryoglobulins. Very rarely, Igs do not precipitate, but, upon cooling, form a gel. Here, we report a case of cryogel observed in a patient presenting with Waldenström's disease. Using proteomic tools, a monoclonal IgM was identified as being the cause of the gel formation. Furthermore, addition of H(2)O before incubation at 4 degrees C demonstrated that the monoclonal IgM was precipitable as a type I cryoglobulin (hypocryoglobulin).

Recent advances in blood-related proteomics

Blood is divided in two compartments, namely, plasma and cells. The latter contain red blood cells, leukocytes, and platelets. From a descriptive medical discipline, hematology has evolved towards a pioneering discipline where molecular biology has permitted the development of prognostic and diagnostic indicators for disease. The recent advance in MS and protein separation now allows similar progress in the analysis of proteins. Proteomics offers great promise for the study of proteins in plasma/serum, indeed a number of proteomics databases for plasma/serum have been established. This is a very complex body fluid containing lipids, carbohydrates, amino acids, vitamins, nucleic acids, hormones, and proteins. About 1500 different proteins have recently been identified, and a number of potential new markers of diseases have been characterized. Here, examples of the enormous promise of plasma/serum proteomic analysis for diagnostic/prognostic markers and information on disease mechanism are given. Within the blood are also a large number of different blood cell types that potentially hold similar information. Proteomics of red blood cells, until now, has not improved our knowledge of these cells, in contrast to the major progresses achieved while studying platelets and leukocytes. In the future, proteomics will change several aspects of hematology.

Nonreducing two-dimensional gel electrophoresis for the detection of Bence Jones proteins in serum and urine

Nonreducing two-dimensional gel electrophoresis (2-DE) is described for the study of immunoglobulin disorders with asynchronous production of single chains. Unlike classical reducing 2-DE, this method can distinguish between complex intact molecules and their free single chains (with different degrees of polymerization) and will thus be helpful for diagnosis of this type of disease. Examples are taken from canine patients, but the method may also be applied to both urine and serum specimens from other species. Nonreducing 2-DE thus represents a useful tool complementary to classical 2-DE, when further information about the appearance of free subunits or modifications of proteins are required, even in the presence of intact molecules.