Diagnostic significance of immunoglobulins in infectious allergic bronchial asthma

In 100 patients with infectious allergic bronchial asthma the levels of IgM. IgG and IgA were determined by Mancini's method and the levels of IgE, tissue and microbial antibodies by the Prausnitz - Küstner test before and after combined treatment carried out under conditions of the microclimate of the salt mines in the village of Solotvino. The data on the content of immunoglobulins in the blood serum allowed the authors to establish 3 types of immediate hypersensitivity. THe decreased content of IgM in the blood serum indirectly revealed the role of immune complexes in the pathogenesis of infectious allergic bronchial asthma. The high content of IgE suggested that atopy could take some part in the infectious process.     

Diagnostic uses of the Hill (Logit and Nernst) plots.

Analysis of the Hill plot for ligand-binding studies shows that it can adopt a variety of shapes other than a straight line. The shape of the curve can yield valuable information about the details of the binding process. In some cases it is possible to discriminate between models of co-operativity without the need for curve-fitting by computer.     

Problem of J-chain of immunoglobulins

Molecules of secretory immunoglobulins (Ig) of classes A and M (sIgA and sIgM) play the main role in protection of mucosae from pathogenic factors. The apparatus of synthesis of these molecules represent the most powerful part of the immune system. One of the key elements of the sIgA and sIgM is J-chain. It represents an acid polypeptide of molecular mass of about 15 kDa composed of 137 amino acid residues including 8 cysteine residues and one site of N-glycosylation. The primary structure of the J-chain is unique: attempts to ascribe it to any family of known proteins so far have failed. The J-chain is inserted into the sIgA and sIgM molecules by forming disulfide bonds with C-terminal sites of α-or μ-chains. It is necessary for formation of IgA dimers and IgM pentamers, for reception of these molecules by epithelial cells, binding of secretory component to them, and for transfer of sIgA and sIgM molecules onto mucosal surfaces and into secrets of exocrine glands. The J-chain has been revealed in the cytoplasm of the early T-and B-lymphocyte precursors not producing Ig. The J-chain is detected in the human embryonic liver cells earlier than the expression of the μ-chain gene begins. Study of mice with knockout of J-chain B-lymphocytes-producers has shown their block of functions of T-helpers providing formation of immunologic memory. Comparison of J-chain genes of mammals, amphibians, reptiles, and cartilaginous fishes has shown the degree of interspecies homology of these proteins to vary from 33% to 70%. The J-chain genes were revealed in representatives of all vertebrate classes except for cyclostomes and bony fishes. In 1996, data were published about the presence of the J-chain genes-homologs in invertebrates, tunicates, and cyclostomes. No papers reproducing or confirming these data have been published. On the contrary, in the literature an opinion appeared that indicate necessity to revise the notion about the presence of J-chain in invertebrates. The main unsolved issues on the J-chain involve the tertiary structure of this protein, its relation to some particular protein family, its functions in cells of the T-and B-lymphocytic differentiation lineages as well as its evolutionary age.     

Unknown functions of immunoglobulins A

Traditionally, the function of immunoglobulins A (IgA), the major type of secreted antibodies, has been thought to be restricted to binding antigens outside the epithelium basal membrane. Therefore, effector mechanisms eliminating IgA-opsonized targets have not been investigated so far. However, some indirect observations of infectious agents penetrating into tissues and blood from the environment suggest such mechanisms (analogous to IgG/IgM-dependent activation of complement and natural killers). In the present review, we examine details of IgA structure that might contribute to elucidation of IgA-dependent effector functions in human and animal immunity. Special attention is given to a putative transduction of signal about antigen binding in the active center of IgA from the Fab- to the Fc-superdomain via intramolecular conformational rearrangements. Different structure of the IgA subclasses (IgA1 and IgA2) is examined taking into account probable divergence of their functions in immune response.     

Ligand-induced structuring of polyreactive immunoglobulins

The influence of several hydrophobic compounds with different structures on the binding of native and chaotropically modified bovine immunoglobulins to native and denatured nonspecific protein immobilized on the surface is researched. It is shown that the character of binding depends on the amount and mutual location of hydrophobic nuclei in the effectors structure. The authors observed moderate suppression of binding or absence of the expressed effect while using one-nucleus effector. The influence of compounds with two distanced benzene nuclei differs qualitatively from the influence of the compound with two condensate ones, described earlier: it was observed that the stimulation level of the binding depends on structural-functional condition of immunoglobulin and immobilized protein. In case of the effector with three spaced hydrophobic nuclei the stimulating effect is much more expressed (3-4 times higher). The concentration dependence of the ligand-induced effects is demonstrated. It is supposed, that stimulative influence of effectors with spaced hydrophobic nuclei is caused by two different processes. The first one is the formation of highly binding center as the result of ligand-induced structuring of immunoglobulins. The other one is the competition for the center formed between dissolved polynuclear effector and ligand groups of aminoacids hydrophobic residues statistically formed on the surface of immobilized protein.     

Economic uses of lichens

Some of these lowly plants have long served as fodder for the reindeer herds of Lapplanders, while others have been the sources of industrial dyes, as those used in the manufacture of Harris Tweed cloth.