Generation and Characterization of Human Single-Chain Antibodies Against Polycyclic Aromatic Hydrocarbons

Immunomodulation of carcinogens-induced steroids-dependent human diseases

The experimental and clinical data about antibodies against environmental chemical carcinogens and endogenous steroids are represented. The conception of immunomodulation of carcinogens- and steroids-dependent human diseases is proposed. It is postulated that antibodies to polycyclic aromatic hydrocarbons and heterocyclic amines in cooperation with antibodies to cholesterol, sex hormones, mineralo- and glucocorticoids stimulate or inhibit cancer, malformation, cardiovascular and autoimmune diseases depending on their personal combination. It is recommended to use immunoassay of these antibodies for the human diseases prediction. The alternative approaches for prevention using the probiotics transformed by anti-carcinogen antibodies are substantiated.

Immunization against environmental chemical carcinogens: Pro and contra

The problems of immunoprotection from the environmental chemical carcinogens are discussed. The main experimental argument pro active immunization against carcinogens is a possibility of specific mucosal antibodies (Abs) to inhibit the penetration of carcinogens from environment and to stimulate its excretion with the following decreasing of carcinogen-DNA adducts levels. Hypothesis of cancer immunostimulation after active immunization against carcinogens is based on a high cancer risk in persons with high levels of serum Abs specific to environmental carcinogens coupled with high levels of Abs to endogenous steroids stimulating the proliferation of target cells, for example, Abs to benzo[a]pyrene together with Abs to estradiol. The active immunization could increase the cancer risk much more in those persons. The passive immunization could be an alternative safe approach to avoid this problem.

Isolation, production, and characterization of a new single chain anti-idiotypic antibody against benzo[a]pyrene

Polycyclic aromatic hydrocarbons are chemical carcinogens which could induce the development of human cancers. Anti-idiotypic antibodies against benzo[a]pyrene (BP) are perspective for human cancer immunoprophylaxis and tumor immunodiagnostic techniques. The purpose of this study was to isolate anti-idiotypic antibodies against BP from human lymphocytes naïve phage library. The anti-idiotypic antibody, named B5, was selected. Analysis of the nucleotide and amino acid sequences B5 showed no similarity to known protein databases antibodies. B5 bound idiotypic antibodies against BP in direct and competitive ELISA. It was suggested that the B5 carried an immunological image of BP and bound the idiotypic antibodies against BP.

ABBREVIATIONS

scFv: single-chain variable fragment; Ab1: idiotypic antibodies; Ab2: anti-idiotypic antibodies; CBD: cellulose binding domain; BSA: bovine serum albumin; PBS: phosphate buffer; BP-BSA: benzo[a]pyrene-BSA conjugate; Cr-BSA: chrysene-BSA conjugate; Py-BSA: pyrene-BSA conjugate; Ac-BSA: anthracene-BSA conjugate; Ba-BSA: benz[a]anthracene-BSA conjugate; PAH: polycyclic aromatic hydrocarbons; pSh: mouse idiotypic single-chain variable fragment against benzo[a]pyrene; T72: human idiotypic single-chain variable fragment against benzo[a]pyrene.

New human single chain anti-idiotypic antibody against benzo[a]pyrene

The nal¨ve library from the lymphocytes of healthy humans was screened by murine single-stranded idiotypic antibodies against benzo[a]pyrene (pSh). The phage clone which contained of anti-idiotypic antibody against benzo[a]pyrene, designated as A4, was chosen for further work because of highly specific to pSh. The available protein databases were searched. The A4 amino acid sequence was unique and 76% identical to a sequence in antibody against interferon g. The A4 protein was expressed in bacteria and purified by two different methods: His-tagged A4 and CBD-fusion A4. Both the A4 bound to pSh and also to the human single chain idiotypic antibody against the benzo[a]pyrene (T72) by ELISA. The K_d values of A4 for pSh and T72 were very close: 4.44 × 10^-7 M and 5.71 × 10^-7M, respectively. A4 was a competitor with benzo[a]pyrene for binding sites of both idiotypic pSh and T72 in competitive ELISA. Thus, A4 was a high affinity anti-idiotypic against benzo[a]pyrene which recognised pSh and T72 active sites.