It was shown that polyreactive immunoglobulins (PRIG), which are capable to interact non-specifically with various antigens, could differ from so called natural antibodies, which have also the capacity to react non-specifically with various antigens, including self-antigens. The main differences are that in contrast to the natural antibodies, which mainly interact, probably, with hydrophilic epitopes, PRIG recognise and bond preferentially to hydrophobic epitopes. We can consider this binding as a new type of interaction between immunoglobulins and antigens.