Activation of spleen lymphocytes by plasmid DNA

Plasmid pUC19 DNA was shown to stimulate in vitro proliferation of CBA mous e splenocytes in a dose-dependent manner. Simultaneous treatment of the cel ls with the plasmid DNA and Con A or LPS produced an additive effect, while PMA acted synergistically with DNA. Monovalent Fab fragments of rabbit ant i-mouse Ig (RAMIg) antibodies significantly inhibited plasmid DNA-induced p olyclonal lymphocyte activation suggesting the involvement of Ig receptors in this process. Affinity modification of lymphocytes membrane-cytosole pro teins with a P-32-labeled alkylating oligonucleotide derivative resulted in labeling of 67-82 and 23 kDa polypeptides corresponding to IgD and ISM hea vy and light chains respectively. The immunoglobulin nature of the 67-82 an d 23 kDa oligonucleotide-binding polypeptides was confirmed by immunoprecip itation with RAMIg antibodies. (C) 1999 Elsevier Science Ltd. All rights re served.