Monoclonal antibodies to a benzo[a]pyrene diolepoxide modified protein

Monoclonal antibodies have been developed which specifically recognize protein modified by 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE-I). These antibodies have been characterized as to sensitivity and specificity by an enzyme-linked immunosorbent assay. They react with BPDE-I-modified proteins and do not cross-react with non-modified protein. All the antibodies have higher sensitivity toward BPDE-I-tetraols than to BPDE-I-modified protein. They cross-react with BPDE-I-deoxyguanosine, BPDE-I-DNA and BPDE-II-rabbit serum albumin. Because of the high antibody sensitivity for tetraols, an immunoassay was developed for quantitating DNA and protein adducts based on release of tetraols from modified samples. This approach was validated using radiolabeled BPDE-I modified DNA and protein.

Quantitation of exposure to benzo[a]pyrene with monoclonal antibodies

It is now possible to quantitate carcinogen adducts on DNA by highly sensitive immunoassays. These techniques are particularly useful for screening human populations for exposure to potential environmental carcinogens. We have developed a panel of monoclonal antibodies that react with benzo(a)pyrene (BP) modified DNA to be used in an enzyme linked immunoassay (ELISA) to quantitate adduct levels of both human and animal samples. BALBc/Cr mice were immunized with either DNA modified by 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9, 10-tetrahydrobenzo(a)pyrene (BPDE-I-DNA) complexed electrostatically to methylated bovine serum albumin or with BPDE-I-modified guanosine conjugated with bovine serum albumin (BPDE-I-G-BSA). Four stable clones were produced from the spleen cells of animals immunized with BPDE-I-DNA and one from BPDE-I-G-BSA immunized animals. All antibodies were shown to be highly specific for BPDE-I-DNA and did not crossreact with nonmodified DNA or with N-2-acetylaminofluorene or 1-aminopyrene modified DNA. The antibodies differed in their sensitivity to BPDE-II-DNA, BPDE-I-poly G, BPDE-I-tetraols and BPDE-I-dG. In general, all the antibodies showed the greatest affinity for their original antigen. Those generated against modified DNA showed highest reactivity against modified DNA while the one antibody generated against the monoadduct showed highest reactivity with the monoadduct. These antibodies are currently being used in a highly sensitive competitive ELISA to quantitate levels of BP-DNA adducts in various animal and human tissue samples.

Monoclonal antibodies to DNA modified by a benzo[a]pyrene diol epoxide

Monoclonal antibodies were obtained after fusion of mouse P3 X 63 Ag8.653 myeloma cells with spleen cells isolated from BALB/cCr mice immunized with either DNA modified by 7 beta, 8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]-pyrene (BPDE-I-DNA) complexed electrostatically to methylated bovine serum albumin or with BPDE-I modified guanosine conjugated with bovine serum albumin, BPDE-I-G-BSA. One monoclonal hybridoma line from each type of immunization was grown as ascites tumors or in defined media and characterized in an enzyme linked immunosorbent assay (ELISA). The antibody produced from the spleen cells of a BPDE-I-DNA immunized mouse, designated 5D11, recognizes BPDE-I-DNA and DNA modified by 7 beta,8 alpha-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE II) but not unmodified DNA, N-2-acetylaminofluorene (AAF) or 1-nitropyrene (NP) modified DNA, BPDE-II-dG or BPDE-I tetraol. It does recognize BPDE-I-dG but with a much lower affinity than when the adduct is present in DNA. In contrast, antibody 8E11 produced from the spleen cells of a BPDE-I-G-BSA immunized mouse recognizes the monoadduct BPDE-I-dG better than BPDE-I-DNA. It also recognizes BPDE-I tetraol but not BPDE-II-DNA, unmodified DNA, AAF- or NP-DNA or BPDE-II-dG. In a noncompetitive ELISA as little as 3 fmol of BPDE-I-DNA adduct can be detected with either antibody 5D11 or 8E11. The combination of the highly sensitive ELISA and highly specific monoclonal antibodies should be valuable in the detection and quantitation of human exposure to benzo[a]pyrene.

Lethal factor released from submandibular grafts in mice

The present series of experiments clearly demonstrates the existence of the lethal factor in the submandibular gland of male BALB/c mice. This lethal factor was released from the submandibular gland of male mice when the glands were transplanted autologously into submandibular-sialoadenectomized male mice or isologously into normal intact adult male or female mice. Neither the sublingual nor the parotid grafts demonstrated the same effect. The lethal effect was not observed in the experiments with submandibular grafts obtained from immature male or mature female mice. As a host, the female mouse was found to be more susceptible to the lethal factor. There was a linear relationship between the strength of the lethal factor and the number of submandibular grafts used. The site of production of the lethal factor is unknown. It was extremely unusual to see the death of host mice which merely received a normal organ other than the submandibular gland.

Testosterone dependency of the lethal factor in mouse submandibular gland isografts

In previous papers we have described the presence of the lethal factor which was exerted by the submandibular glands transplanted from adult male donor mice autologously and isologously. The lethal factor was not demonstrated by submandibular grafts obtained from immature male or adult females. We then hypothesized that the lethal factor may be directly related to sexual maturation of male donors and also to an action of testosterone. To clarify this hypothesis, the present experiments were carried out, and the results obtained indicate that the lethal factor is testosterone-dependent. Submandibular grafts obtained from both immature male and adult female donors which received pretreatment with testosterone enanthate exerted a lethal effect on the hosts. Large dosages of testosterone enanthate, which obviously increased the lethal factor level in the submandibular gland, did not kill normal intact adult mice; nor did it increase the mortality of bilaterally submandibular-sialoadenectomized immature mice beyond that of controls without testosterone treatment, when they were not transplanted. Although the site of production of the lethal factor is unknown, we postulate that the submandibular gland is the source.