'LE cells' result from phagocytosis of apoptotic bodies induced by antinuclear antibodies.

Lupus erythematosus (LE) cells are believed to represent phagocytosis by granulocytes of cell nuclei whose DNA has been 'depolymerized' and opsonized by serum factors, most likely antinuclear antibodies and C3b. Since it is known that certain antinuclear antibodies are capable of inducing apoptosis after intracellular penetration; and that the resulting apoptotic bodies can be ingested by non-professional phagocytes, we decided to investigate the possibility that LE cells could result from the phagocytosis of apoptotic bodies induced by antinuclear antibodies. We demonstrate herein, through different methodological approaches, that the ingested material within LE cells corresponds to apoptotic bodies, and that the LE cell phenomenon can be reproduced, in the absence of other serum factors, by penetrating murine monoclonal anti DNA antibodies.

The effect of humoral immunity against adducted benzo[a]pyrene on DNA damage elicited by acute carcinogen exposure in Swiss mice.

Immunoglobulins G (lgG) specific for benzo[a]pyrene-DNA adducts were elicited in Swiss mice by repeated subcutaneous injections of a high molecular weight benzo[a]pyrene-DNA conjugate-adjuvant mix. The immunization procedure resulted in the production of specific antibodies against adducted benzo[a]pyrene B[a]P in all treated animals. One week after completion of the immunization procedure, groups of ten immunized and ten non immunized female mice were treated by single intraperitoneal injection with two different doses of B[a]P. The mice were sacrificed 48 hours after treatment, and both liver and bone marrow cells were isolated for subsequent determinations of DNA binding and micronucleus induction, respectively. Covalent benzo[a]pyrene adducts in liver DNA were detected by competitive ELISA and the incidence of micronucleated polychromatic erythrocytes was evaluated by scoring one thousand cells per animal. The determination of DNA adducts in liver revealed significantly (p < 0.05) lower levels of B[a]P adducts in immunized mice compared to non-immunized animals at both doses, whereas no significant difference was observed between controls. Administration of benzo[a]pyrene produced moderate, dose-related increases in the incidence of micronucleated polychromatic erythrocytes in all treated groups, with no significant difference between immunized and non-immunized mice. The decrease of covalent DNA adducts in the liver of immunized mice suggests that the specific humoral immunity elicited by repeated carcinogen exposure may act as a relevant modulating factor in chemical carcinogenesis.

Micronuclei in lymphocyte subsets in relation to immune proteins and allergic disease.

This is an investigation of 54 boys and 23 girls with a median age of 19 years (range 18-22 years). The study group contained 12 boys and five girls with asthma and 23 boys and seven girls with allergic rhinitis. Sensitivity to pollen and furred animals were reported by 22 boys and eight girls and by 17 boys and six girls, respectively. The levels of serum immune proteins (IgA, IgE and IgG with subclasses, and IgM) were determined by immunological techniques. As a biomarker of chromosomal damages, the lymphocyte micronuclei was used. We analyzed the frequencies of micronuclei in 3000 B-lymphocytes and in equal numbers of T4- and T8-lymphocytes. The lymphocytes were separated by magnetic attraction in T4 (CD4), T8 (CD8) and B (CD19) fractions using Dynabeads(R). The most interesting finding of this investigation was that the three markers of atopic disease, asthma, hypersensitivity to pollen and IgE levels, associated significantly with increased frequencies of micronuclei in B-lymphocytes. There was also a relation between IgA and the frequency of micronuclei in B-cells. In an epidemiological study of 7000 individuals with allergic diseases, we have found an over-risk for lymphomas in the group with positive skin prick test. Hypothetically, we think that there may be a link between our present finding of an increased mutagenic activity and the lymphoma over-risk among individuals with allergic disease since most lymphomas stem from B-lymphocytes.

Effects of cetirizine dihydrochloride on human lymphocytes in vitro: micronucleus induction. Evaluation of clastogenic and aneugenic potential using CREST and FISH assays.

Cetirizine dihydrocloride, a widely administered antiallergic drug with the amine piperazine in its molecule, was studied as to its ability to cause micronucleus formation in human lymphocyte cultures treated in vitro. Peripheral lymphocytes from four different donors were cultured and treated with different concentrations of the compound. Cetirizine dihydrocloride was shown to induce enhanced micronucleus frequency in a dose-dependent manner, although lymphocytes from the different donors showed different susceptibilities to the compound. The content of induced micronuclei was investigated in one of the four donors by two independent assays, CREST (the application of antikinetochore antibodies) and FISH (fluorescence in situ hybridization) on cytochalasin B-formed binucleated cells. It was shown that the induced micronuclei resulted from breakage events as well as chromosome loss, thus characterizing cetirizine dihydrocloride as both clastogen and aneugen. Since our results were derived only from in vitro experiments, we believe that an extensive in vivo study is necessary before drawing conclusions as to the effects of cetirizine dihydrochloride in patients.