Professor Emeritus
E-mail: roald.nezlin@weizmann.ac.il
Phone: +972-8-934-3652
Location: Wolfson Bldg., Room 716
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Professor Roald Nezlin, M.D. Professor Emeritus E-mail: roald.nezlin@weizmann.ac.il Phone: +972-8-934-3652 Location: Wolfson Bldg., Room 716 |
Research Interests:
Quantitative studies of DNA levels in immune complexes at experimental SLE and in SLE Patients
A simple immunochemical dot blot assay, which allows not only to detect specific immune complexes (IC) but also to characterize them quantitatively, was developed (1). By this assay, the DNA antigen levels in IC circulating in mice with experimental SLE were detected. On day 12 after SLE induction the levels of DNA in IC were sharply increased but thereafter began to decrease before the first SLE manifestations were seen and later when SLE disease was fully developed. The early appearance of circulating IC after induction of the disease was responsible at least partly for the SLE clinical manifestation, which developed much later. The decrease of the DNA levels in IC in the later phases of SLE was probably due to the deposition of IC in the kidneys (3).
A large group of SLE patients at different stages of the disease and a group of healthy donors was studied on the presence of circulating DNA: anti-DNA IC. All studied healthy persons had significant amounts of DNA: anti-DNA immune complexes, which were formed by nucleosomes and natural autoantibodies circulating in blood ("natural IC"). The lower levels of DNA in IC (even below the normal levels) were found three times often in patients with SLE activity than in patients with inactive form of SLE. The latter group of SLE patients usually had significantly elevated levels of DNA in IC (4).
We determine the levels of DNA in circulating IC in serial samples from 28 patients with SLE by the dot blot assay and investigate their possible relationship to clinical variables such as disease activity clinical subsets, drug treatment, and also to the levels of C1q and other complement components. The levels of DNA in IC decrease significantly before flares and continue to be low during flares in patients with low serum concentrations of C1q (5). The assay for detection of antigens in IC used in these studies could be a valuable diagnostic test for the evaluation of the prognosis of SLE (6).
Expressed Immunoglobulin Repertoire of unimmunized mice
The repertoire of isolated Ig polypeptide chains synthesized by LPS-stimulated splenic B cells from unimmunized 6 weeks old mice was studied by 2D gel electrophoresis. These B cells formed mainly mu heavy chains, while only a small amount of gamma chains was detected on 2D electrophoregrams. The number and character of spots corresponding to each class and type of H and L chains were analyzed. Most of the detected 52 spots, which corresponded to L chains, were well resolved with clearly defined round boundaries. Six of them belonged to two isotypes of lambda chains and the rest to the kappa chain. About 25 clusters corresponded to mu chains. They had different appearance from those of L chains and their characteristic elliptic form with prolonged vertical axes indicated the presence of several H chain variants of slightly different length (due to the length variations of CDR3 and carbohydrate heterogeneity) in each cluster. The limited number of spots both of H and L chains is explained as being due to restrictions in the expressed repertoire of preimmune splenic B cells, which have no somatic mutations in the Ig genes (7).
Immobilization of proteins on paper carrier
Oxidized paper is used as an insoluble carrier for immobilization of proteins (8). On a spot of 1 cm diameter about 15 micrograms of a protein can be immobilized. Antibodies immobilized on paper retain their specific Ag-binding activity and can be applied as a very sensitive measurement tool.
Presence of IgG-CD4 complexes in the human circulation
CD4 T-cell membrane glycoprotein was found in the complexes with IgG molecules isolated from healthy donor sera and sera of SLE patients via a sensitive quantitative dot-blot assay (9). The CD4 part of the complexes has a mol. mass of about 50 kDa and hence is build from all 4 extracellular CD4 domains.
The Book and Reviews
The book entitled "The Immunoglobulins. Structure and Function" (10) was published by Academic Press (San Diego). The first comprehensive review of the immunoglobulin literature in over 20 years, the book describes the basic structural features of immunoglobulin molecules, and how detailed knowledge of their structure illuminates their functrional role in the immune response. Several other topics are discussed:
- the localization and structure of all knowing binding sites of immunoglobulin molecules
- studies of immunoglobulin flexibility
- properties of immunoglobulin-binding molecules other than antigens
- recently developed techniques for creating fully active antibodies and new variant of immunoglobulins in vitro.
Genetic events responsible for antibody variability (VDJ recombination, somatic mutations, and class switch recombination) are discussed in (11).
Structural and functional aspects of interactions of immunoglobulin molecules with various ligands of animal, bacterial, viral and synthetic origin are discussed in a comprehensive review (12).
The recent data on the presence of the IgG complexes of the non-immune nature in the human circulation are summarized in a review (13). By the association with serum IgG, proteins including potentially harmful ones can be eliminated from the circulation. Some proteins absent in the liquid phase of blood or present in very low concentrations could be found only in complexes with IgG. Quantitative studies of the IgG associated proteins could give valuable clinical information on various pathologies as important disease markers could be found among these proteins. Functional aspects of the complex formation are discussed.