Abstract
Antibodies reacting with chromosomal proteins as well as their complexes with DNA in HeLa cells can be elicited by immunization with dehistonized HeLa chromatin preparations. Most of these antibodies recognize specific complexes of nonhistone proteins and DNA. Complement fixation assays show that treatment of HeLa chromatin or nuclei with cross-linking agents (UV or gamma irradiation, 1,3-bis(chloroethyl)-1-nitrosourea (BCNU), or cis-diamminedichloroplatinum (cisplatin)) significantly increases immunological reactivity with specific antisera. This suggested that these agents cross-linked the antigenic nonhistone proteins to DNA and thus stabilized the antigenic nonhistone protein-DNA complexes.