Treatment Of Human Peripheral Blood Lymphocytes Research Articles

Mangiferin, a glucosylxanthone, protects against the radiation-induced micronuclei formation in the cultured human peripheral blood lymphocytes

The effect of mangiferin (MGN), a glucosylxanthone, derived from Mangifera indica was studied on the radiation-induced DNA damage in the cultured human peripheral blood lymphocytes (HPBLs) by micronucleus assay, where HPBLs were treated with 0, 5, 10, 20, 50, 100 μg/ml of mangiferin 30 min before exposure to 3 Gy of 60Co γ-radiation. Treatment of HPBLs with 50 μg/ml reduced the radiation-induced micronuclei to the maximum extent. Irradiation of HPBLs to 0, 1, 2, 3, or 4 Gy resulted in a dose-dependent increase in the frequency of micronuclei, while treatment of HPBLs with 50 μg/ml MGN before exposure to 0, 1, 2, 3, or 4 Gy of 60Co γ-radiation resulted in a significant decline in the frequency of micronuclei when compared with the untreated irradiation group.

Effect of mangiferin on radiation-induced micronucleus formation in cultured human peripheral blood lymphocytes

Irradiation causes a variety of lesions in important biomolecules of the cell through generation of free radicals leading to genomic instability. DNA strand breaks, acentric fragments, or defective kinetochores are manifested as micronuclei after the first cell division. Chemicals that can trap free radicals may reduce the deleterious effects of ionizing radiation. Mangiferin (MGN), a glucosylxanthone derived from Mangifera indica (mango), was investigated for its ability to reduce the frequency of radiation-induced micronucleated binucleate cells (MNBNCs) in cultured human peripheral blood lymphocytes (HPBLs). HPBL cultures were pretreated with 0, 5, 10, 20, 50, and 100 microg/ml of MGN for 30 min before exposure to 3 Gy of (60)Co gamma-radiation. The maximum decline in radiation-induced micronuclei was observed at a concentration of 50 microg/ml MGN; thereafter, a nonsignificant elevation in MNBNC frequency was observed at 100 microg/ml MGN. Since the lowest MNBNC frequency was observed for 50 microg/ml MGN, dose-response studies were undertaken using this concentration. Irradiation of HPBLs with 0, 1, 2, 3, or 4 Gy of gamma-radiation caused a dose-dependent elevation in the MNBNC frequency, while treatment of HPBLs with 50 microg/ml MGN 30 min before radiation resulted in significant declines in these frequencies. MGN alone did not alter the proliferation index. Irradiation caused a dose-dependent decline in the proliferation index, while treatment of HPBLs with 50 micro/ml MGN significantly elevated the proliferation index in irradiated cells. MGN treatment reduced hydrogen peroxide-induced lipid peroxidation in HPBLs in a concentration-dependent fashion. In cell-free studies, MGN inhibited the induction of (.)OH (hydroxyl), O(2) (.-) (superoxide), DPPH (1,1-diphenyl-2-picrylhydrazyl), and ABTS(.+) (2,2-azino-bis-3-ethyl benzothiazoline-6-sulphonic acid) radicals in a dose-dependent manner. The results of this study indicate that MGN possesses radioprotective properties by suppressing the effects of free radicals.

Evaluation of the radioprotective effect of Aegle marmelos (L.) Correa in cultured human peripheral blood lymphocytes exposed to different doses of gamma-radiation: a micronucleus study.

The radioprotective effect of a hydroalcoholic extract of Aegle marmelos (AME) was evaluated in cultured human peripheral blood lymphocytes (HPBLs) by the micronucleus assay. The optimum protective dose of the extract was selected by treating HPBLs with 1.25, 2.5, 5, 6.25, 10, 20, 40, 60, 80 and 100 microg/ml AME before exposure to 3 Gy gamma-radiation and then evaluating the micronucleus frequency in cytokinesis blocked HPBLs. Treatment of HPBLs with different doses of AME reduced the frequency of radiation-induced micronuclei significantly, with the greatest reduction in micronucleus induction being observed for 5 microg/ml AME. Therefore, this dose of AME was considered as the optimum dose for radioprotection and further studies were carried out treating the HPBLs with 5 microg/ml AME before exposure to different doses (0, 0.5, 1, 2, 3 and 4 Gy) of gamma-radiation. The irradiation of HPBLs with different doses of gamma-radiation caused a dose-dependent increase in the frequency of lymphocytes bearing one, two and multiple micronuclei, while treatment of HPBLs with 5 microg/ml AME significantly reduced the frequency of lymphocytes bearing one, two and multiple micronuclei when compared with the irradiated control. The dose-response relationship for both groups was linear. To understand the mechanism of action of AME separate experiments were conducted to evaluate the free radical scavenging of OH, O2(-), DPPH, ABTS(+) and NO in vitro. AME was found to inhibit free radicals in a dose-dependent manner up to a dose of 200 microg/ml for the majority of radicals and plateaued thereafter. Our study demonstrates that AME at 5 microg/ml protected HPBLs against radiation-induced DNA damage and genomic instability and its radioprotective activity may be by scavenging of radiation-induced free radicals and increased oxidant status.

Heterogeneity of human lymphocyte Fc receptors: Studies using heat-aggregated and antigen-complexed IgG from human, rabbit, guinea pig, horse and goat

We have studied the ability of human peripheral blood lymphocytes (HuPBL) 4 to interact with IgG from several animal species. Three functions or activities that are reported to depend on an interaction between complexed IgG and HuPBL receptors (R) for the Fc piece of IgG (FcγR) were compared: (1) antibody-dependent cell-mediated cytotoxicity (ADCC); (2) binding of heat-aggregated IgG (aggG); and (3) rosette formation with IgG-sensitized erythrocytes [RBC-A(γ)]. IgG (and IgM) antibodies to chicken erythrocytes (CRBC) were purified from the sera of the following species after injection with CRBC stroma: (1) horse (Ho); (2) goat (Go); (3) rabbit (Ra); and (4) guinea pig (Gp). Good IgG-agglutinating antibody titers were obtained from each injected species. Using 51Cr-labeled CRBC targets and HuPBL effector cells, only Ra anti-CRBC IgG gave good ADCC at high dilutions. Ho and Go anti-CRBC (IgG) failed to give AD̄CĊ, and Ḡp anti-CRBC (IgG) gave approx. 30% of the level of kill as Ra. Ra Fab' 2 fragments of IgG antibody failed to produce ADCC. Treatment of HuPBL with Ra anti-lymphocyte serum (ALS) almost totally ablated ADCC, whereas HoALS failed to alter ADCC. Pretreatment of HuPBL with aggG showed that Ra or Hu aggG gave essentially equal inhibition of ADCC, Gp gave approx. 30% of the degree of inhibition as Hu and Ra, and Ho or Go aggG had essentially no effect of ADCC. These results confirmed the following order of ability of IgG to interact with HuPBL ADCC killer (K) cells: (Hu ⪖)Ra > Gp ⪢ Ho, Go. The data suggest that Gp IgG interacts with only a subpopulation (≈ 30%) of HuPBL K cells. The binding of aggG to total HuPBL failed to strictly correlate with the ADCC results or with the results of rosette formation between total HuPBL and CRBC-A(γ). The observations suggest that there is a heterogeneity of FcγR between K and non-K cell subpopulations of HuPBL both in terms of the type of complexed IgG they are able to bind, and in terms of the species of origin of the IgG. The data also support contentions that FcγR that bind RBCA(γ) complexes differ from those that bind aggG.