INVOLVEMENT OF SURFACE IMMUNOGLOBULINS IN LYMPHOCYTE-ACTIVATION BY PLASMID DNA

A study was made of the mitogenic effect of plasmid DNA on in vitro pr oliferation of CBA mouse splenocytes. The effect became detect able at 50 ng/ml DNA and was dose-dependent. The effects of DNA and another m itogen were additive (ConA or LPS) or synergistic (PMA). Rabbit antimo use antibodies and their monovalent Fab fragments significantly inhibi ted DNA-induced polyclonal lymphocyte activation, thus demonstrating t he involvement of Ig receptors in this process. The interaction of a P -32-labeled alkylating oligonucleotide derivative with proteins of the lymphocyte membrane-cytoplasm fraction was studied. A number of prote ins specifically interacting with oligonucleotides were detected (K-d ranged 0.5 to 5 mu M). They included 72K, 67K, and 25K polypeptides co rresponding in size to IgM and IgD chains.