Tag Archives: antigens

Kinetics of interaction between polyreactive immunoglobulins and antigen

S. A. Bobrovnik1*, O. V. Ogloblya2, M. O. Demchenko1, S. V. Komisarenko1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, Ukraine;
*e-mail: s-bobrov@ukr.net

Received: 28 January 2020; Accepted: 25 June 2020

A number of experimental kinetics curves of mice polyreactive immunoglobulins (PRIGs) binding to ovalbumin immobilized on immunologic plates were obtained at different temperatures. Analysis of these curves allowed us to conclude that the model of PRIGs interaction with antigens proposed by us earlier and consisted on PRIGs activation (i.e. exposition of hydrophobic patches on PRIGs surface) and either sequential binding to antigen or  inactivation was is in a good agreement with the experimental data obtained in this study. We have designed a method of the rate constants evaluation from experimental binding curves. It was found  that the rate constant of the activated PRIGs binding to immobilized antigen did not depend on temperature. The rate constant of PRIGs activation occurred to be depend on temperature more strongly than the rate constant of PRIGs inactivation. We have concluded from the acquired dependences that at 37°С the number of activated PRIGs was 15 times higher than that at 0°С.

Kinetic parameters of polyreactive immunoglobulins interaction with antigens in the presence of protamine

S. A. Bobrovnik, M. O. Demchenko, S. V. Komisarenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: s-bobrov@bk.ru

The discovered earlier phenomenon of the enhancment of polyreactive immunoglobulines (PRIGs) binding to antigens in the presence of protamine and Tween 20 was investigated in more details. The comparative analysis of PRIGs reaction dynamics with immobilized antigen was provided. In addition, the rate constants for the reaction and the affinity constants of PRIGs-antigen binding in the presence or absence of optimal protamine concentration were determined. The rate constant of PRIGs-antigen reaction did not increase in the presence of protamine optimal concentration and was even reduced approximately twice. However, in the presence of protamine the concentration of reactive PRIGs molecules, that were able to interact with antigen, increased approximately 30 times, and this led to strong reaction rate increase. Protamine also influenced the affinity constant of PRIGs-antigen binding, which increased approximately three times. The suggestion was made that such protamine effect was due to its influence on the PRIGs molecules special structure, and, as a result of the conformational change PRIGs became able to bind more effectively to the antigens.

Fundamental differences between natural antibodies and polyreactive immunoglobulins

S. A. Bobrovnik, M. A. Demchenko, S. V. Komisarenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: s-bobrov@bk.ru

A problem of similarity and differences between so-called polyreactive immunoglobulins (PRIGs) and natural antibodies (NAbs), capable of cross-reacting with some structurally dissimilar antigens, has been considered. The analysis of mechanisms of an unspecific interaction between PRIGs or NAbs and antigens evidences for the fact that essential differences exist between these substances. These differences permit classifying the abovementioned substances as different types of immunoglobulin molecules. The major difference between PRIGs and NAbs may include both the mechanisms of the above mentioned immunoglobulin molecules binding to antigens and their interaction affinity, as well as an absolutely different influence of some low-molecular substances on the efficiency of the interaction with antigens. Relying on the obtained data it can be assumed that, since PRIGs and NAbs have fundamental differences, they may perform not only similar but also different functions of the immune system.

Biological and immunochemical properties of polyreactive immunoglobulins

S. A. Bobrovnik, M. A. Demchenko, S. V. Komisarenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: s-bobrov@bk.ru

A previously unknown phenomenon of acquired polyreactivity of serum immunoglobulins, which were subject to the effect of concentrated solutions of chaotropic ions, such as KSCN (3.0-5.0 M), low/high pH (pH 2.2-3.0), or heating to 58-60 °C, was originally described by the authors in 1990. Eleven years after that, similar data were published by J. P. Bouvet et al.(2001), which confirmed completely our results concerning the influence of either chaotropic ions or drastic shift of pH on polyreactive properties of immunoglobulins. Our further investigations (1993, 1995, 1998) of polyreactive serum immunoglobulins (PRIG) properties have revealed that the mechanism of nonspecific interaction between PRIG and antigens much differs from the mechanism of interaction between specific antibodies and corresponding antigens. Later we have shown that the increase in PRIG reactivity could be induced in vivo (1999) and PRIG are one of serum components of human or animal sera. Then, it could be suggested that PRIG may perform certain biological functions. Studying PRIG’s effect on the phagocytosis of microbes or on the tumor growth (S. A. Bobrovnik et al., 1995, 1998) have revealed that PRIG may play a certain role in protecting the body from infections and probably may influence the development of various pathological processes. Recently we also found (S. A. Bobrovnik et al., 2014) that IgG PRIG content significantly increases in aged people. These data demonstrate that further investigations of PRIG’s immunochemical properties and study of their biological role in organism protection from various diseases is very important.