Teflon Bag Research Articles

Selective induction of delayed hypersensitivity T-effector and T-suppressor lymphocytes in vitro by haptenized bone marrow-derived macrophages

The role of various subpopulations of antigen-presenting macrophages in the induction of T-lymphocyte subpopulations has been difficult to study in the past. We have used an in vitro system of bone marrow cell culture both to induce T-effector (T DH) and T-suppressor (T S) cells active in delayed-type hypersensitivity. Bone marrow-derived macrophages (BM-MA) grown in Teflon bag cultures were allowed to attach to culture dishes and were pulse-labeled with 2,4-dinitrobenzene sulfonate (DNBSO 3). Spleen cell lymphocytes from nonsensitized BALB/c mice were cocultured with antigen-pulsed or control BM-MA for 3 days. The lymphocytes were harvested, and injected iv into BALB/c mice which were challenged within 1 hr after injection by painting the right ear with 2,4-dinitrofluorobenzene (DNFB, effector test) or sensitized with DNFB on 2 days following iv injection of the cells and challenged 5 days later (suppressor test). Ear swelling was measured 24 hr later to assess the effector or suppressor function of the in vitro educated lymphocytes. BM-MA grown for 5 days (BM-MA 5) in L-cell conditioned medium induced only T DH cells (Thy 1 +, Lyt 1 +2 −) whereas BM-MA grown for 10 days in conditioned medium induced only T, cells (Thy 1 +, Lyt 1 −2 +). In both cases, induced T DH and T S cells were antigen specific. Functionally, induced T, cells suppressed the afferent limb of the delayed response. When DNP-BM-MA 5 and DNP-BM-MA 10 were used to induce T DH or T S cells in vivo by subcutaneous or intravenous injection respectively, only BM-MA 5 were able to sensitize recipient mice. Both 5- and 10-day macrophage populations induced T s cells in vivo. Functionally, these T S cells appeared to act on the efferent limb of the delayed reaction. We conclude that different populations of antigen-presenting macrophages can preferentially induce T DH or T S cells, perhaps depending on antigen presentation in association with class II antigens or on the functional state of the antigen-presenting cell.

Gas-to-particle conversion in photochemical smog: Aerosol growth laws and mechanisms for organics

Experiments were conducted to determine particle growth rates as a function of particle size in the presence of reacting organic gases. Hydrocarbons and oxides of nitrogen were added to unfiltered ambient air in an 80 m 3 Teflon bag exposed to natural solar radiation. The ensuing photochemical reactions resulted in growth of the particles originally present. The size distribution of the evolving aerosol was measured in the size range above 0.3 μm using a single particle optical counter. From the change in the size distribution with time, the particle growth rate was determined as a function of size and time. The results could be explained by a mechanism based on diffusion to the particles of condensable gases formed by chemical reaction, with a critical particle size below which growth did not occur (Kelvin effect). A growth law corresponding to this mechanism was used to compute a smog aerosol size distribution which agreed well with atmospheric measurements.

Photochemical aerosol formation. Sulfur dioxide, 1-heptene, and NOx in ambient air

Aerosol formation was studied in a 96-m/sup 3/ Teflon bag containing unfiltered ambient air to which small amounts of SO/sub 2/, 1-heptene, and NO/sub x/ had been added. The contents were irradiated by sunlight. Gas phase concentrations were monitored continuously and a rate law was determined for the reaction of 1-heptene. By simultaneous measurements of the conversion of SO/sub 2/ and the formation of particulate sulfur, a sulfur balance was carried out on the system. The distribution of sulfur with respect to particle size, as well as total aerosol sulfur and carbon, was measured as a function of time during the experiments. The rates of formation of condensable species of both sulfur and carbon are consistent with a reaction between SO/sub 2/ and a reactive intermediate of the O/sub 3/-1-heptene reaction. The distribution of sulfur with respect to particle size shows a bimodal distribution about 0.2 ..mu..m.

Measurements of aerosols produced by the photochemical oxidation of SO 2 in air

The formation and growth of aerosols produced by the photooxidation of SO 2 in initially particle-free air was measured and characterized over the size range from 0.0040μm to 0.4 μm using a Whitby Aerosol Analyzer and a Condensation Nuclei Counter. The experiments were conducted in a photochemical reaction chamber consisting of a 625 ft 3 Teflon bag illuminated with fluorescent ultraviolet lamps. The same basic pattern of aerosol formation and growth was observed over the range of SO 2 concentrations from 0.049 to 2.88 ppm. The particle volume concentration increased linearly with time indicating a steady condensation of material from the vapor to the condensed phase. The number concentration increased rapidly, reached a maximum value, and then decayed uniformly by coagulation. After an initial rapid increase, the surface area concentration approached an equilibrium value which correlated strongly in a power function relationship with the volumetric conversion rate. Also, the volume mean diameter of the growing particles was found to increase linearly with time at a rate which correlated strongly with the volumetric conversion rate. In the early stages of nucleation and growth the volume concentration exhibited a nonlinear increase with time which was thought to reflect the variation in the condensation rate of material during the nucleation phase. Calculated values of the overall photooxidation rate of SO 2 in air adjusted to noon-day sunlight ranged from 0.379 to 0.992%/hr. Estimates of the partial pressure of H 2SO 4 vapor at the onset of nucleation ranged from 1.72 × 10 −8 to 1.2 × 10 −7 mm Hg.

The effect of water vapor on ozone synthesis in the photo-oxidation of alpha-pinene.

A study of the effect of water vapor on the photochemical system NO2 + alphapinene + hv was conducted. A Hotpack Environmental Room was used as a constant temperature chamber, a bank of ultraviolet and fluorescent lamps as a source of simulated solar radiation, and a 150-liter FEP Teflon bag as a reaction vessel. Representative concentrations of 10 pphm NO2 and 50 pphm alphapinene were used in a 3 × 2 × 2 factorial design where absolute humidities of 0.0000, 0.0090, 0.01 80 g H2O/g dry air were varied. Matheson zero air was passed through a clean air train and used as the diluent. Nitrogen dioxide was added to the reaction mixture by a permeation tube, and water and alpha-pinene by evaporation techniques. Variables measured as a function of time over a 2-hour irradiation period were total oxidants (Mast Ozone Meter), condensation nuclei (General Electric Small Particle Detector), ozone (Regener Chemiluminescent Ozone Meter), nitrogen dioxide and nitric oxide (Technicon Autoanalyzer), and alpha-pinene (Per...