Antarctic teleost immunoglobulins: more extreme, more interesting

We have investigated the immunoglobulin molecule and the genes encoding it in teleosts living in the Antarctic seas at the constant temperature of −1.86 °C. The majority of Antarctic teleosts belong to the suborder Notothenioidei (Perciformes), which includes only a few non-Antarctic species. Twenty-one Antarctic and two non-Antarctic Notothenioid species were included in our studies. We sequenced immunoglobulin light chains in two species and μ heavy chains, partially or totally, in twenty species. In the case of heavy chain, genomic DNA and the cDNA encoding the secreted and the membrane form were analyzed. From one species, Trematomus bernacchii, a spleen cDNA library was constructed to evaluate the diversity of VH gene segments. T. bernacchii IgM, purified from the serum and bile, was characterized. Homology Modelling and Molecular Dynamics were used to determine the molecular structure of T. bernacchii and Chionodraco hamatus immunoglobulin domains. This paper sums up the previous results and broadens them with the addition of unpublished data.     

Histocompatibility antigens,autoantibodies, and immunoglobulins in alcoholic liver disease.

Determination of histocompatibility antigens in 63 patients with alcoholic liver disease showed that HLA-B8 was more prevalent in patients with cirrhosis than in controls, but among those with fatty liver and minimal fibrosis the prevalence of this antigen was normal. Another noticeable difference was the absence of HLAA28 in the cirrhotic group. In the total series of 219 patients the prevalence of antinuclear and smooth muscle antibodies was raised; they were especially prevalent in patients with cirrhosis. Raised serum IgA and IgG concentrations were also common (found in 50% and 37% respectively) and were again significantly associated with cirrhosis. In contrast, serum IgM levels, which were raised in 46% of cases, were not significantly related to the presence of cirrhosis but correlated significantly with the degree of portacaval shunting. These results support recent evidence suggesting that immune responses may be implicated in alcohol-induced liver damage, particularly in its progression to cirrhosis.     

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.     

Investigations of magnesium, histamine and immunoglobulins dynamics in acute urticaria

In 42 urticaria patients, magnesium, histamine and IgE were dosed. Magnesium, IgE and histamine variations were followed in urticaria evolution, during acute phase and clinical remission. We noticed magnesium, histamine, IgE values variations depending on disease evolution and applied therapeutic scheme. Therefore: At disease starting point, histamine presented 3.5 times higher values than the normal ones. The value decreases following a curve which tends to reach normal values during clinical remission. At disease starting point, magnesium presented values under the inferior limit of the normal, 0.5 m mol/L respectively, as a mean. The value increases towards the normal limit during clinical remission. Immunoglobulins E follow a similar curve to histamine one, presenting 1,250 U/L values at the starting point, that, under medication, influence decrease between normal limits (800 U/L), during clinical remission. Analyzing the variations of biochemical parameters, the authors emphasize magnesium substitution treatment in urticaria.     

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.