Establishment of B cell hybridomas with B cell surface antigens

M12.4, one of several B lymphomas derived from BALB/c mice, was mutagenized with ethyl methanesulfonate in vitro. M12.4.1, a subline of the mutant cells, was sensitive to hypoxanthine-aminopterin-thymidine selective medium and was fused with normal splenic B lymphocytes of C57BL/6ByJ mice. The hybridomas obtained from this fusion were shown to express mu heavy chain, H-2KbDb, Iad, and Iab on the cell surface by analyses of flow microfluorometry and a cytotoxicity assay, although parental M12.4.1 lacked mu heavy chain on the cell membrane. These results demonstrate that the B cell hybridomas with B cell surface antigens have been established in vitro. IgM molecules on the cell surface of the hybridomas were shown to originate from normal B cells of C57BL/6ByJ mice by flow microfluorometry analyses after staining with fluorescein-labeled Bet 1, a monoclonal rat antibody that recognizes Igh-6.5, a mouse IgM allotypic determinant. These hybridomas could generate IgM-secreting cells at the high frequency (more than 10% of the cultured cells) when stimulated with bacterial lipopolysaccharide. On the other hand, parental M12.4.1 did not develop any IgM-secreting cells under the same conditions. These findings suggest that these B cell hybridomas with B cell surface antigens may be a good model for the study of B cell differentiation.

Establishment of B cell hybridomas with B cell surface antigens

M12.4, one of several B lymphomas derived from BALB/c mice, was mutagenized with ethyl methanesulfonate in vitro. M12.4.1, a subline of the mutant cells, was sensitive to hypoxanthine-aminopterin-thymidine selective medium and was fused with normal splenic B lymphocytes of C57BL/6ByJ mice. The hybridomas obtained from this fusion were shown to express mu heavy chain, H-2KbDb, Iad, and Iab on the cell surface by analyses of flow microfluorometry and a cytotoxicity assay, although parental M12.4.1 lacked mu heavy chain on the cell membrane. These results demonstrate that the B cell hybridomas with B cell surface antigens have been established in vitro. IgM molecules on the cell surface of the hybridomas were shown to originate from normal B cells of C57BL/6ByJ mice by flow microfluorometry analyses after staining with fluorescein-labeled Bet 1, a monoclonal rat antibody that recognizes Igh-6.5, a mouse IgM allotypic determinant. These hybridomas could generate IgM-secreting cells at the high frequency (more than 10% of the cultured cells) when stimulated with bacterial lipopolysaccharide. On the other hand, parental M12.4.1 did not develop any IgM-secreting cells under the same conditions. These findings suggest that these B cell hybridomas with B cell surface antigens may be a good model for the study of B cell differentiation.

Thymic responses to antigen challenge. I. Tumor cells induced phenotypic and functional changes in vivo

Thymocytes from mice bearing a footpad injection of 2 x 10(6) syngeneic tumor cells exhibited increased in vitro responsiveness to concanavalin A and allogeneic cells in the mixed lymphocyte reaction. A higher proportion of Thy 1 dull cells (assayed by flow microfluorometry) was seen among thymocytes taken from normal, or control injected mice, relative to tumor injected mice. Injection of culture supernatant from the tumor cells induced no phenotypic or functional shifts among thymocytes, nor was any evidence of viral gp70 antigen expression found in the thymocyte preparation. These findings support the notion that viruses or viral products are not involved in induction of these shifts; however, lymphokine production by host peripheral cells has not been ruled out.

Effects of lung inflation on alveolar epithelial solute and water transport properties

Paired hollow bullfrog lungs (Rana catesbeiana) were used to study the effects of lung inflation on alveolar epithelial transport of water and hydrophilic solutes. Frogs were double pithed and the lungs were removed after bronchial placement of a Lucite plug. Three openings in the plug accommodated the insertion of two agar-Ringer bridges (for electrical potential measurement and passage of direct current) and the injection and removal of alveolar bathing fluid. Ringer solution containing a tracer quantity of radioactive solute was instilled into the lung sacs (5 ml or 50 ml) and the lungs were suspended in baths of Ringer solution containng appropriate cold solutes (5 mM). Permeability properties of each solute (and water) were determined from the rate of radiotracer concentration change in the bath. The spontaneous potential difference, tissue resistance, and solute permeability properties determined in these experiments showed no significant differences between the 5- and 50-ml lungs. Assuming homogeneous, cylindrical water-filled pores to be present in the tissue, the equivalent pore radii estimated from the rates of solute and water fluxes were 1.1 (for 5-ml lungs) and 0.9 nm (for 50-ml lungs). After overinflation of the lung (to greater than 80 ml), experiments at 50 ml yielded a pore radius of 3.4 nm. These data suggest that passive alveolar epithelial transport properties do not change with degrees of lung inflation normally encountered in vivo but that overinflation can lead to increased leakiness of the barrier.

Effects of exposure to acid on alveolar epithelial water and solute transport

Water and solute transport properties of normal and acid-exposed bullfrog alveolar epithelium were determined under controlled conditions. Paired lungs from the same animal were studied in Ussing chambers. Tissue bioelectric parameters, permeabilities of water and solutes, and hydraulic conductivity were measured. Results from control lungs were compared with those observed after the alveolar epithelium was exposed to acid (pH 2.0-4.0) for variable periods of time (1-60 min). Acid exposure appears to initially damage tissue active transport mechanisms, causing a marked fall in potential difference at pH less than or equal to 3.0. Increases in tissue conductance and permeability to solutes occurred after a variable time lag. Water permeability did not change after acid exposure. Equivalent homogeneous pore radius increased as time of exposure to acid increased. It is concluded that the bullfrog alveolar epithelium, normally resistant to water and solute flux, loses its ability to transport ions actively and gradually becomes leaky after exposure to acid (pH less than or equal to 3.0). The pathway for movement of water across alveolar epithelium may be different from that for solutes.

Ia antigen-bearing B cell tumor lines can present protein antigen and alloantigen in a major histocompatibility complex-restricted fashion to antigen-reactive T cells

Several Ia-positive BALB/c B cell tumor lines were screened for their ability to present alloantigen and protein antigens to alloreactive and antigen-reactive T cells. Of six Ia-positive tumor lines studied, three were found to be effective as antigen presenting cells (APC). Indeed, on a per cell basis, one of the stimulatory lines, A20.3, was substantially more effective than whole spleen cells. The other three lines, although Ia-positive, were nonstimulatory. A20.3 was chosen for further study. This tumor appeared to behave like the conventional APC because (a) the tumor cells presented alloantigen, (b) they presented protein antigen in an MHC-restricted fashion to both primed donor T cells and to long-term continuous T cell lines, (c) alloantigen presentation was blocked by the inclusion of an anti-Ia antibody in the culture system, and (d) A20.3 cells could be effectively pulsed with antigen, although the continuous presence of antigen in the culture system resulted in a superior response. The addition of an exogenous source of interleukin 1 proved necessary to obtain an alloreactive but not an antigen-specific T cell response, although its inclusion did enhance the magnitude of antigen-stimulated proliferation. These tumor cells should prove useful in studying the biochemical events that occur during antigen processing and the requirements for T cell triggering by processed antigen in association with Ia molecules.

Transport of water and solutes across bullfrog alveolar epithelium

Water and solute transport properties of the alveolar epithelium of isolated bullfrog lungs were studied. Lungs from Rana catesbeiana were removed and mounted in an Ussing chamber. Unstirred layers on both sides of the tissue were estimated from the time courses of dilution potential development, and the measured transport parameters were corrected for the effect of the unstirred layers. Spontaneous potential difference, short-circuit current, tissue resistance, instantaneous voltage-current relationships, diffusional permeabilities of water and hydrophilic solutes, and hydraulic conductivities were determined. The hydraulic conductivity obtained from hydrostatically driven water flow anomalously decreased with time, and was initially 100 -1,000 times higher than osmotically determined hydraulic conductivity. The equivalent pore radius of the bullfrog alveolar epithelium was estimated to be 0.8-0.9 nm. We conclude that the alveolar epithelium is extremely tight, presenting a major barrier to water and solute flow. This high resistance to water and solute flow may be helpful in maintaining the alveolar lumen relatively free of fluid under normal physiological conditions.

Monoclonal antibodies to stage-specific, species-specific, and cross-reactive antigens of the rodent malarial parasite, Plasmodium yoelii

Eighteen hybridoma cell lines were used to study species-specific, stage-specific, and serological cross-reactive antigens of the rodent malarial parasite, Plasmodium yoelii. Specificity and location of plasmodial antigens were determined by indirect fluorescent-antibody analysis. Results showed that a minimum of 12 distinct plasmodial antigens could be distinguished by the 18 hybridomas. Antigens were found on the surface or within the cytoplasm of the parasite, but not on the surface of erythrocytes from infected animals. The majority (11 of 12) of antigens were present in all erythrocytic stages of the parasite, but one was stage-specific for merozoites. Additional studies showed that 6 of 18 of the monoclonal antibodies identified species-specific antigens, 2 of 18 recognized antigens confined to related rodent malarial parasites (Plasmodium berghei, Plasmodium vinckei, and Plasmodium chabaudi), whereas 8 of 18 detected cross-reactive antigens common to rodent, primate (Plasmodium knowlesi, Plasmodium falciparum), and avian (Plasmodium gallinaceum) malarias.

Radioimmunoassay for detecting antibodies against murine malarial parasite antigens: monoclonal antibodies recognizing Plasmodium yoelii antigens

A solid-phase radioimmunoassay (SPRIA) in microtiter wells was established for detecting antibodies against Plasmodium yoelii Ag. The SPRIA was found 1) to require as little as 5 micrograms of crude parasite Ag per well, 2) to be able to detect 0.5 ng of monoclonal Ab, and 3) to be 10(4) times more sensitive than the indirect fluorescent Ab staining technique. In a modification of the above assay using intact RBC as an Ag, hyperimmune serum showed significant binding to the surface of erythrocytes of mice infected with P. yoelii parasites but not to RBC of normal mice. Hybridomas were prepared by fusing infected mouse spleen cells with P3-NS1/I-Ag4-1 myeloma cells. Using the SPRIA, hybrids secreting Ab against P. yoelii 17XL Ag were detected. All the hybrids detected by SPRIA secreted Ab binding to free parasites but not to the surface membrane Ag on the infected RBC. The number of positive hybrids produced by fusing spleen cells from mice given a double infection (17XNL and 17 XL) was not greater than that produced by freezing spleen cells from mice given a single infection (17 XL).

Radioimmunoassay for detecting antibodies against murine malarial parasite antigens: monoclonal antibodies recognizing Plasmodium yoelii antigens

A solid-phase radioimmunoassay (SPRIA) in microtiter wells was established for detecting antibodies against Plasmodium yoelii Ag. The SPRIA was found 1) to require as little as 5 micrograms of crude parasite Ag per well, 2) to be able to detect 0.5 ng of monoclonal Ab, and 3) to be 10(4) times more sensitive than the indirect fluorescent Ab staining technique. In a modification of the above assay using intact RBC as an Ag, hyperimmune serum showed significant binding to the surface of erythrocytes of mice infected with P. yoelii parasites but not to RBC of normal mice. Hybridomas were prepared by fusing infected mouse spleen cells with P3-NS1/I-Ag4-1 myeloma cells. Using the SPRIA, hybrids secreting Ab against P. yoelii 17XL Ag were detected. All the hybrids detected by SPRIA secreted Ab binding to free parasites but not to the surface membrane Ag on the infected RBC. The number of positive hybrids produced by fusing spleen cells from mice given a double infection (17XNL and 17 XL) was not greater than that produced by freezing spleen cells from mice given a single infection (17 XL).

Transport of water and solutes across sheep visceral pleura

The fluid and solute transport properties of pleural tissue were studied using specimens of intact visceral pleura from adult sheep lungs. After thoracotomy, a shallow incision through the pleural surface permitted 10-cm2 by 10-micrometer pieces of visceral pleura free of lung parenchyma to be peeled off the lung surface. The pleura was then mounted as a planar sheet separating 2 reservoirs of Krebs-Ringer solution. Electrical potential and resistance, hydraulic water permeability, and diffusional permeability to water and several hydrophilic solutes were measured. The results showed that (1) no spontaneous voltage difference was present across the pleura; (2) electrical resistance (27.1 omega/cm2) was very low; (3) hydraulic water permeability was extremely high (1.64 X 10(-8) ml/dyne-s); and (4) diffusional permeability was high, varying from 5.24 X 10(-4) cm/s for water to 4 X 10(-5) cm/s for hemoglobin. Blue dextran (molecular weight, 2 X 10(6) daltons) did not cross the pleura in measurable quantities. We concluded that the isolated visceral pleura of the adult sheep is an extremely "leaky" tissue that probably does not actively transport salt and water. These findings are consistent with a passive model of pleural fluid formation and reabsorption, and suggest that the transport properties of normal pleural tissue are unlikely to be responsible for any differences in composition between interstitial and pleural fluids.