Natural antibodies (NAb) are found in the serum of healthy individuals. The
se antibodies are produced without any apparent specific antigenic stimulat
ion. They are one part of the circulating immunoglobulins and are found in
virtually all vertebrate species. NAb react to various self- and non-self a
ntigens. A protective function in different infection models could be demon
strated. Several groups have reported the ability of NAb to bind to tumour
cells. Their possible role in tumour defence is documented in mice. The pre
sent status of attempts to characterise the role of NAb in tumour defence i
s discussed, particularly as regards the human immune system. This paper fo
cuses on antibody-cell interactions and discusses the genetic background of
the Nab-producing B-cells. (C) 1999 Elsevier Science B.V. All rights reser
ved.