Studies on immunity in hybridoma-bearing mice. B. Immunity against the hybridoma. I. Studies on the immune state of mice after rejection of the hybridoma

Anti-dinitrophenyl IgE secreting hybridoma B 53 cells may be rejected when injected subcutaneously in BALB/c mice. These mice are immune as they withstand without any ill effect the intraperitoneal injection of LD100 B 53 cells. Sera from mice which rejected the tumor have cytotoxic antibodies against the hybridoma, as shown by in vitro tests, but serum cannot transfer immunity to naive BALB/c mice against hybridoma B 53. Spleen cells from mice which have rejected the tumor might transfer immunity against B 53 hybridoma, and with Winn tests it has been shown that these spleen cells are very effective against the B 53 cells and also against the myeloma cells which were used for the fusion to construct the B 53 hybridoma. Subcutaneously injected B 53 cells not only produce anti-DNP IgE secreting tumors, but often also metastasize to spleen, and they are sometimes detected in the circulating blood. Mice with splenic metastasis or with detectable circulating B 53 cells generally die. However, we did observe one mouse with splenic metastasis which successfully rejected the tumor and became immune to B 53 cells.

Cofilin, a protein in porcine brain that binds to actin filaments and inhibits their interactions with myosin and tropomyosin

Cofilin, a 21 000 molecular weight protein of porcine brain, reacts stoichiometrically with actin in a 1:1 molar ratio. Upon binding of cofilin, the fluorescence of pyrene-labeled actin under polymerizing conditions is changed into the monomer form, irrespective of whether cofilin is added to actin before or after polymerization. Cofilin decreases the viscosity of actin filaments but increases the light-scattering intensity of the filaments. The centrifugation assay and the DNase I inhibition assay demonstrate that cofilin binds to actin filaments in a 1:1 molar ratio of cofilin to actin monomer in the filament and that cofilin increases the monomeric actin to a limited extent (up to 1.1-1.5 microM monomer) in the presence of physiological concentrations of Mg2+ and KCl. Cofilin is also able to bind to monomeric actin, as demonstrated by gel filtration. Electron microscopy showed that actin filaments are shortened and slightly thickened in the presence of cofilin. No bundle formation was observed in the presence of various concentrations of cofilin. The gel point assay using an actin cross-linking protein and the nucleation assay also suggested that cofilin shortens the actin filaments and hence increases the filament number. Cofilin blocks the binding of tropomyosin to actin filaments. Tropomyosin is dissociated from actin filaments by the binding of cofilin to actin filaments. Cofilin was found to inhibit the superprecipitation of actin-myosin mixtures as well as the actin-activated myosin ATPase. All these results suggest that cofilin is a new type of actin-associated protein.

Correlation of murine anti-dinitrophenyl antibody content as determined by ELISA, passive cutaneous anaphylaxis and passive hemolysis

Antibody contents of IgG1, IgG2a, IgG2b and IgE were measured by enzyme-linked immunosorbent assay (ELISA) in ascites and sera obtained from mice injected with hybridomas producing monoclonal anti-DNP antibodies. In addition, IgG1 and IgE antibodies from sera of immunized mice were also measured by ELISA. Concomitantly, antibody contents were also determined by passive cutaneous anaphylaxis (PCA) in mice for IgG1, IgG2a, IgG2b, by PCA in guinea pigs for IgG2a, by PCA in rats for IgE and by passive hemolysis (PL) for IgG2a and IgG2b. Good correlations were found in the investigated samples between ELISA and the biological determinations.

Characterization of the action of porcine brain profilin on actin polymerization

When porcine brain actin is polymerized in either KCl/MgCl2 or KCl alone, porcine brain profilin prolongs the lag phase and inhibits the rate and extent of polymerization in a concentration-dependent manner. Profilin also decreases the elongation rate in a concentration-dependent manner. Moreover, addition of profilin to steady-state actin filaments causes slow depolymerization. All these actions of profilin are explainable by a monomer sequestering mechanism. The inhibition by profilin of both the extent of polymerization and the elongation rate is stronger in KCl alone than in KCl/MgCl2. Moreover, it was found that brain profilin inhibits the polymerization of brain actin more strongly than that of muscle actin. Brain 88K protein/actin complex (88K/A), which has been shown to cap the barbed end of actin filaments, potentiates the inhibitory action of profilin; i.e. the extent of polymerization is much more reduced by profilin in the presence of 88K/A than in its absence.

Isolation of low molecular weight actin-binding proteins from porcine brain

Three new actin-binding proteins having molecular weights of 26,000, 21,000, and 19,000 were isolated from porcine brain by DNase I affinity column chromatography. These proteins were released from the DNase I column by elution with a solution of high ionic strength. They were further purified by column chromatographies using hydroxyapatite, phosphocellulose, and Sephadex G-75. All of these actin-binding proteins behaved as monomeric particles in the gel filtration chromatography. After elution of the three actin-binding proteins, actin and profilin were recovered from the DNase I column with 2 M urea solution. The eluted was further purified by a cycle of polymerization and depolymerization and finally by gel filtration. Little difference in polymerizability was detected between the purified brain actin and muscle actin. After sedimentation of the polymerized brain actin, profilin was purified by DEAE-cellulose and gel filtration column chromatographies. In the assay of the action of these actin-binding proteins, the 26K protein was found to cause a large decrease in the rate of actin polymerization, while showing little effect on the extent of polymerization. The 21K protein decreased the steady-state viscosity of actin solution in a concentration-dependent manner irrespective of whether it was added before or after actin polymerization. It reacted with actin at a 1:1 molar ratio.

Action of a 19K protein from porcine brain on actin polymerization: a new functional class of actin-binding proteins

A 19K protein isolated from porcine brain not only inhibits actin polymerization but depolymerizes actin filaments quickly. The protein reacts stoichiometrically with actin in a 1:1 molar ratio. When actin is induced to polymerize with salts in the presence of the brain 19K protein, the lag phase is prolonged, and the extent of polymerization is decreased, but the half-polymerization time is not increased. This can be explained by assuming that the 19K protein severs growing actin filaments and thus causes an increase in the number of filament ends during the polymerization process, thereby accelerating the overall polymerization. Moreover, the low-shear viscosity of actin filaments is reduced much more than the high-shear viscosity by the 19K protein, suggesting that actin filaments become shorter in the presence of the 19K protein than in its absence. Actin filament depolymerization by the 19K protein is much faster than that by brain profilin or than spontaneous depolymerization. This indicates that the 19K protein depolymerizes actin filaments not only by sequestering actin monomers but also by directly attacking the filaments. The number of actin filaments, measured by assaying the nucleating ability, is increased by substoichiometric concentrations of the 19K protein, irrespective of whether the protein is added to actin monomers before polymerization or added to performed actin filaments. These results suggest that the brain 19K protein not only stabilizes actin monomers but also cuts actin filaments, thereby decreasing the extent of actin polymerization and also changing the filament length. The action on actin of the actin-depolymerizing protein from starfish oocytes resembles that of the brain 19K protein, although the molecular weight of the starfish protein is slightly smaller. The brain 19K protein and starfish protein should be classified into a new functional group of actin-binding proteins.

Systemic vascular lesions and prognosis in systemic lupus erythematosus

The purpose of this paper is to show the relationship of systemic vascular lesions to the clinical manifestations and prognosis in SLE. Thirty-four autopsied cases of SLE formed the subject material for this study. Histopathological tissue studies were made on vascular lesions from almost all organs. Vascular lesions were separated into three groups according to the size of the involved vessel: 1) medium-sized artery (9 cases), 2) small artery (12 cases) and 3) (13 cases) without systemic vascular lesions. Vascular lesions were also separated into five groups (a) fibrinoid degeneration (10 cases), b) intimal thickening (6 cases), c) thrombosis (6 cases), d) sclerosis (7 cases) and e) (13 cases) without systemic vascular lesions. Patients with involvement of medium-sized arteries had a low female incidence, photosensitivity, and positive LE cell incidence, and the cause of death in these patients was cerebral vascular involvement. The cause of death in patients with vascular fibrinoid degeneration and thrombosis was mainly uremia, whereas patients with sclerosis more often died from infection. Regarding systemic vascular lesions in SLE, the prognosis for the patients with thrombosis and vascular involvement of medium-sized arteries was the most grave.

Purification and partial characterization of a new protein in porcine brain which bundles actin filaments

A new protein capable of bundling actin filaments was purified from porcine brain by ammonium sulfate fractionation and Sephacryl S-300, hydroxyapatite and Whatman DE 52 column chromatographies. Co-sedimentability of this protein with actin filaments on low speed centrifugation was used as an index in the purification process. This protein had a molecular weight of 53,000 as estimated by SDS-polyacrylamide gel electrophoresis. The Stokes' radium of the protein was determined to be 3.3 nm by the gel filtration method, which indicates a monomeric form of the protein in solution. On isoelectric focusing, it showed a single protein band having a pI of 5.62. This protein caused bundling of actin filaments as seen on electron microscopy, thereby lowering the specific viscosity of the actin solution in a concentration-dependent fashion. The bundling activity of the 53K protein was modulated by changes in ionic strength and pH of the medium as well as by ATP and Mg ions. Low shear falling ball viscometry showed the formation of a gelling structure on mixing of actin filaments with this portion.

Kinetic and thermodynamic analyses of outer doublet tubulin polymerization

The kinetics and thermodynamics of microtubule assembly were studied using outer doublet tubulin isolated from starfish sperm. Purified tubulin was gel-filtered just prior to the experiments. The self-polymerization process was found to be characterized by a lag followed by a growth phase that did not show a single first-order decay reaction. This suggested that the nucleation and elongation steps are not completely separate. The maximal rate of polymerization and the reciprocal of the duration of lag time increased approximately in proportion to the third and second powers of tubulin concentration above the critical concentration, respectively. Measurement of temperature dependence of the critical concentration gave a linear van't Hoff plot with delta H degree = 13.5 kcal/mol and delta S degree = 69 e.u.

A protein in starfish sperm head which bundles actin filaments in vitro: purification and characterization

From an extract of starfish sperm heads, a protein was purified using ammonium sulfate fractionation, Sephacryl S-300, hydroxyapatite and Whatman DE 52 columns. Co-sedimentability on low speed centrifugation of this protein with actin filaments was used as an index in the purification. This protein has a molecular weight of 57,000, as judged by SDS-polyacrylamide gel electrophoresis. It lowers the specific viscosity of an actin filament solution, although this effect is abolished under high ionic conditions such as 300 mM NaCl. Electron microscopic observation shows formation of actin filament bundles with a banding pattern of about 10 nm periodicity. Based on these results, we call this protein starfish sperm fascin. Changes in pH and Mg2+ or ATP concentration have no effect on the action of this sperm fascin. Neither the rate of actin polymerization nor that of depolymerization is affected by this protein. The bundles are depolymerized as well by actin-depolymerizing protein (Mabuchi, I. (1981) J. Biochem. 89, 1341-1344) purified from starfish eggs.

Follow-up study of pharyngeal carriers of beta-hemolytic streptococci among school children in Sapporo City during a period of 2 years and 5 months

A total of 124 normal school children in three classes (aged 8 to 9) were examined for beta-hemolytic streptococci for 29 months from August 1977 to December 1979 be means of serial monthly throat cultures. No significant difference between the carrier rate of boys and that of girls was observed. Although no monthly variation of carrier rates appeared in class II, marked temporal increases of carrier rates appeared from June 1978 (in Class I) and from August 1978 (in class III) in August 1979. These periodical variations of carrier rates observed in this investigation do not coincide with the low-in summer and high-in winter seasonal variations which has generally been observed by many other investigators. The average values of carrier rates throughout the period of this investigation were 30.9, 29.7, and 24.5% in classes I, II, and III, respectively. The carrier rate of group A streptococci by month and by class showed some positive correlation with the carrier rate of total beta-hemolytic streptococci. T-type 4 and T-untypable strains were not identified up to a certain period; then each strain appeared at a given time during the course of our investigation in one class, spread to all three classes, and continued to be isolated until the end of this investigation. The origin of these type of strains could not be identified in this study. Of the children, 36 (29.0%) never became streptococcal carriers during the period of examination and 88 (71.0%) became streptococcal carriers at least one time during the 29 examinations; among these positive carriers, 29 children (23.0%) showed positive results in more than 50% of the examinations.

A new regulatory protein that affects the state of actin polymerization

A new protein factor that regulates the state of actin polymerization was purified from porcine brain by DNase I-agarose chromatography. The purified protein factor consisted of a 1 : 1 complex of 88,000 dalton polypeptide and actin. When actin was polymerized by salt in the presence of the factor, the steady-state viscosity and the sedimentability were greatly reduced. The extent of the reductions was found to be greater in the presence of Ca2+ than in its absence.

Dissociation constant of Tetrahymena tubulin-colchicine complex

Tetrahymena tubulin has a very low affinity for colchicine. The dissociation rate constant (k-1) and association rate constant(k+1) of Tetrahymena tubulin for colchicine were determined in comparison with those of porcine brain tubulin. The k+1 value of Tetrahymena tubulin was about one-twentieth that of porcine brain tubulin, and k-1 of Tetrahymena tubulin was about 680 times greater than that of brain tubulin. The dissociation constant (k-1/k+1) of Tetrahymena tubulin (2.7 X 10(-3) turned out to be ten thousand times greater than that of brain tubulin. This large Kd value explains well the high colchicine concentration requirement reported to block cell division of cilia regeneration of this protozoan.