FUNDAMENTAL DIFFERENCES BETWEEN NATURAL ANTIBODIES AND POLYREACTIVE IMMUNOGLOBULINS.

S A Bobrovnik,S V Komisarenko,M A Demchenko

doi:10.15407/ubj87.05.046

Abstract

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.

Highlights

The discovery of polyreactive immunoglobulins (PRIGs), capable of unspecific binding to various antigens [1], has raised a lot of questions
What is the mechanism of this interaction? Are PRIGs just a result of experimental effects on specific monoclonal or polyclonal serum antibodies or are they present in the intact animal and human sera? What may be the biological role of PRIGs? That was one of the main questions: were the obtained PRIGs identical to so-called natural antibodies (NAbs), which had been known and well-studied before [2,3,4,5,6], or PRIGs are a separate subpopulation of immunoglobulins existing in vivo and performing their special functions? To answer these questions we had to perform a lot of different experiments, most of them were connected with interaction between PRIGs and antigens
It is known that NAbs are primarily cross-reacting and low-specific antibodies, that makes them similar to serum PRIGs, which we have found

Summary

Materials and Methods

Human serum albumin (HSA), ovalbumin and horse myoglobin were used in this work as antigens These reagents were commercial products of the Sigma company, USA. Antigens were immobilized on 96-well polystyrene plates produced by Dunatech Company by two different methods, depending on whether the plates were intended for investigation of mAbs and specific serum antibodies, or nonspecific PRIGs. To study the interaction between specific antibodies or mAbs and ovalbumin, the plates were covered with ovalbumin by the traditional method, i.e., by incubation of ovalbumin solution (concentration 10-15 μg/ ml in 0.15 M phosphate buffer, at pH 8.5-9.0) in the wells of the plates during 24 h at 4 °C with further thorough rinsing of plates from unbound antigen immediately before the experiment. After color development of the mentioned substrate, the reaction was stopped by adding 0.06 ml of 2.0 M sulfuric acid to each well, and the optical density of the plate wells was measured by ELx800, BIO-TEK microphotocalorimeter, at 490 nm wavelength

Results and Discussion

PRIG binding to anatoxin A B C

Specific antibodies

Characteristic of the process of binding to antigens