Old mice recover the ability to produce IgG and high-avidity antibody following irradiation with partial bone marrow shielding

The splenic plaque-forming-cell (PFC) response to trinitrophenylated bovine gamma globulin of 18- to 20-month-old mice is markedly depressed, with a preferential loss of indirect (IgG) PFC and high-avidity-antibody-secreting cells compared to 6- to 8-week-old animals. The anti-trinitrophenyl response of old mice, whose peripheral lymphoid system has been reconstituted from their own bone marrow after irradiation while their bone marrow was partially shielded, includes high-avidity and IgG PFCs relatively comparable to those of normal young mice. If young mice are irradiated while their bone marrow is partially shielded and given purified splenic T cells from either old or young donors during recovery from irradiation, then the avidity distribution and the ratio of IgG/IgM PFCs they produce in response to trinitrophenylated bovine gamma globulin reflects the characteristic immune response of the T-cell donor. These results are consistent with the hypothesis that the bone marrows of old and young mice are similar with regard to the spectrum of B-cell clones that they can generate and that it is peripheral regulatory effectors that are responsible for much of the age-related change in the immune response. In addition, if one calculates the PFC avidity distribution taking into account those cells whose secretion of antibody was inhibited by anti-idiotype autoantibodies, then it is clear that there are more high-avidity B cells present in old mice than are detected by the conventional plaque-inhibition assay. Thus, the reduced avidity of the PFC response of old mice appears to be, at least in part, due to down regulation by anti-idiotype autoantibodies.

Regulation of antibody secretion by hybridoma cells. I. Suppression of antibody secretion by coculture of hybridoma cells with idiotype-induced suppressor cells

In this study, we have demonstrated that antibody secretion by hybridoma cell lines can be down-regulated by idiotype-specific immune spleen cells or by nylon wool nonadherent spleen cells. This suppression of antibody secretion can be abolished by treating the idiotype-specific immune spleen cells with anti-Thy 1.2 plus complement. The hybridoma we used for most of our experiments secretes IgM specific for the cross-reacting haptens 2,4,6-trinitrophenyl (TNP) and 2,4-dinitrophenyl (DNP). Suppression was achieved by direct coculture of hybridoma cells with immune cells from animals which were injected with affinity-purified hybridoma antibody-coupled syngeneic spleen cells. The suppressed and control cultures contained similar numbers of viable hybridoma cells, suggesting that a simple cytotoxic effect is not responsible. Idiotype specificity was established in experiments showing that two idiotype immune animals immunized with antibody from two different IgM anti-TNP hybridomas could suppress the hybridoma to which they were immunized but could not affect the other hybridoma. Immune spleen cells required 3-4 days of coculture with hybridoma cells before maximum suppression was achieved. The kinetics of the response suggest that the final effector suppressor cell is generated during the coculture period and that a second signal, perhaps a product of the hybridoma cells, may be required.

Ribavirin pharmacodynamics in high-risk patients for acquired immunodeficiency syndrome

Ribavirin was administered orally in escalating doses for 2 or 4 weeks to 15 symptom-free, human immunodeficiency virus seropositive homosexual men with generalized lymphadenopathy. Reverse transcriptase activity was inhibited during therapy when steady-state plasma concentrations were greater than 6 mumol/L. These concentrations were achieved with 1200 or 2400 mg/day for 2 weeks or a loading dose of 2400 mg/day for 3 days followed by 600 mg/day for 4 weeks. Drug accumulation occurred at all doses. The elimination half-life appeared to be approximately 2 weeks. Reversible adverse reactions, principally resulting in central nervous system symptoms and anemia, correlated with dose and duration of therapy. Immunologic enhancement of T-lymphocyte-mediated mitogen-induced responses was observed in the majority of patients who had reduction in reverse transcriptase activity. However, specific T4+ lymphocyte-mediated antigen-induced responses increased to within the normal range in only three patients. Significant enhancement appeared to correlate with the severity of baseline antigen-induced functional impairment. These data indicate that oral ribavirin can be given for at least 1 month with acceptable toxicity at doses that appear to inhibit human immunodeficiency virus replication.

Reversible blockage of neurite development and growth cone formation in neuronal cultures of a temperature-sensitive mutant of Drosophila

It has been suggested that the membrane recycling process in the Drosophila mutant shibirets1 (shits1) is reversibly blocked at restrictive temperature (greater than 29 degrees C) in various cell types, including neurons, as a result of enhanced vesicle fusion and disrupted membrane pinch-off (Poodry and Edgar, 1979; Koenig et al., 1983; Kosaka and Ikeda, 1983a, b). We analyzed the neuronal development of shits1 cells at the single-cell level by using dissociated larval CNS culture. Compared to normal cultures, there was a substantial reduction in neuronal adhesion to the substratum and a retardation of growth cone formation in shits1 cultures at 30 degrees C. Time-lapse studies showed that neurite initiation and elongation in shits1 cultures were suppressed at the restrictive temperature. Differentiated shits1 neurons exhibited accelerated reabsorption and retarded arborization of neurites at 30 degrees C. The above processes were reversible since normal outgrowth was restored when the temperature was lowered. These findings provide a new line of evidence that growth cone activity determines neurite initiation, elongation, and branching. Furthermore, if the primary defect of the shits1 mutation indeed resides in a membrane recycling mechanism common to different cell types, our results would also lend strong support to the notion that membrane recycling is crucial in the regulation of neuronal membrane adhesion and growth cone activity.

Role of the thymus and T-cells in slow growth of B16 melanoma in old mice

Clinical observations suggest that tumors grow more slowly in aged subjects. To investigate the influence of age on tumor growth, we injected the same number of cultured B16 melanoma cells into C57BL/6 mice of various ages. B16 melanoma cells, inoculated s.c., grew more slowly in old (18-20-month-old) as compared to young (6-8-week-old) mice. In young tumor-bearing mice there was a significant increase in the number and the proliferative response to phytohemagglutinin and concanavalin A of splenic T-cells as compared to old tumor-bearing animals. There was no difference in the response of B-lymphocytes from old and young tumor-bearing mice to lipopolysaccharide. The positive association between T-cells and the rate of tumor growth was also suggested by the slower growth of melanoma cells in thymectomized or thymectomized and anti-theta antiserum-treated young mice. Finally, the age-associated difference in tumor growth could be transferred by spleen cells from old or young mice to thymectomized and lethally irradiated syngeneic young animals. Young mice with rapidly growing B16 melanoma tumors have increased numbers and proliferative responses of thymic-derived lymphocytes. It is likely that T-cells or their products facilitate the growth of B16 tumor cells.

Regulation of antibody production by hybridoma cultures. I. Anti-idiotype antibody-mediated down-regulation of anti-DNA antibody production by hybridoma cells

A series of anti-DNA antibody-producing hybridomas were obtained by fusing spleen cells from 6-month-old MRL/lpr, autoimmune prone, mice with P3X63-Ag8 myeloma cells. Rabbit anti-idiotype (id) antibodies specific for several of the hybridoma proteins were prepared. It was shown that the anti-id antibody inhibited immunoglobulin in secretion by the hybridoma cells in an id-specific manner. Inhibition of antibody production was not due to a cytotoxic effect, since the anti-id, in fact, stimulated proliferation of the hybridoma cells.

Treatment of infections due to multiresistant Neisseria gonorrhoeae with sulbactam/ampicillin

Between January and April 1984, 229 of 448 male patients with urethritis at the Choong-Ku Venereal Disease Clinic in Seoul had positive urethral cultures: 66 for penicillinase-producing Neisseria gonorrhoeae (PPNG) and 163 for non-penicillinase-producing N. gonorrhoeae (non-PPNG). Forty-five men with PPNG urethritis were enrolled in a study of the efficacy of treatment with sulbactam/ampicillin plus probenecid. Diagnosis and evaluation of cure were based on culture results. The agar-plate dilution method was used for susceptibility testing, and the chromogenic cephalosporin test was used for detection of beta-lactamases. MICs of various antibiotics for the isolates were high. MICs of sulbactam/ampicillin were 0.25-4 micrograms/ml, with an MIC90 of 4 micrograms/ml, a value 16-fold lower than that for ampicillin alone (MIC90 greater than 32 micrograms/ml). Patients were treated with 1 g of probenecid orally and either one vial of sodium sulbactam/ampicillin or two vials intramuscularly. Each vial contained 0.5 g of sodium sulbactam and 1 g of sodium ampicillin. Patients were followed up for three to five days. All patients but one were cured, and no remarkable adverse reactions were noted. The two regimens of sulbactam/ampicillin were equally effective in the treatment of uncomplicated PPNG in men.

T cell proliferation induced by anti-self-I-A-specific T cell hybridomas. Evidence of a T cell network

Allo-I-A-reactive T cell hybridomas were generated from MLR-activated lymphoblasts. Cloned hybridomas T1.203, T1.321, and T1.426 were stimulated by I-Ab determinants, as shown by their ability to secrete IL-2 in response to a panel of MHC-recombinant mice. T2.146, T2.205, and T3.116 were found to be specific for I-Ak determinants using a similar panel of MHC-recombinant mice. Inhibition of IL-2 secretion by anti-I-A mAb confirmed these data. Some I-Ab-specific hybrids stimulated the proliferation of T cells from C57BL/6 (H-2b) mice. Similarly, some I-Ak-specific hybrids stimulated the proliferation of T cells from C3H/HeJ (H-2k) mice. These hybrids expressed no detectable surface I-A, and stimulation of T cells was not inhibited by anti-I-A mAb. These results are consistent with the hypothesis that normal mice possess a population of T cells responsive to idiotypic determinants on anti-MHC class II T cell receptors.

The subcellular localization of glutamate dehydrogenase (GDH): is GDH a marker for mitochondria in brain?

Glutamate dehydrogenase (GDH, EC 1.4.1.2) has long been used as a marker for mitochondria in brain and other tissues, despite reports indicating that GDH is also present in nuclei of liver and dorsal root ganglia. To examine whether GDH can be used as a marker to differentiate between mitochondria and nuclei in the brain, we have measured GDH by enzymatic activity and on immunoblots in rat brain mitochondria and nuclei which were highly enriched by density-gradient centrifugation methods. The activity of GDH was enriched in the nuclear fraction as well as in the mitochondrial fraction, while the activities of other "mitochondrial" enzymes (fumarase, NAD-isocitrate dehydrogenase and pyruvate dehydrogenase complex) were enriched only in the mitochondrial fraction. Immunoblots using polyclonal antibodies against bovine liver GDH confirmed the presence of GDH in the rat brain nuclear and mitochondrial fractions. The GDH in these two subcellular fractions had a very similar molecular weight of 56,000 daltons. The mitochondrial and nuclear GDH differed, however, in their susceptibility to solubilization by detergents and salts. The mitochondrial GDH could be solubilized by extraction with low concentrations of detergents (0.1% Triton X-100 and 0.1% Lubrol PX), while the nuclear GDH could be solubilized only by elevated concentrations of detergents (0.3% each) plus KCl (greater than 150 mM). Our results indicate that GDH is present in both nuclei and mitochondria in rat brain. The notion that GDH may serve as a marker for mitochondria needs to be re-evaluated.

An immunochemical study of the pyruvate dehydrogenase deficit in Alzheimer's disease brain

The activity of the pyruvate dehydrogenase complex (PDHC; EC 1.2.4.1, EC 2.3.1.12, and EC 1.6.4.3) was reduced to about 30% of control values in histologically unaffected occipital cortex of the brains of patients with Alzheimer's disease, as well as in histologically affected frontal cortex. In contrast, activity of another mitochondrial enzyme, glutamate dehydrogenase, was normal. Neither age nor time until postmortem study correlated significantly with PDHC activity in either Alzheimer or control samples, and PDHC was not inactivated significantly on incubation with homogenates of either Alzheimer or control brain. Antibodies against the highly purified bovine PDHC inhibited Alzheimer and control PDHC equally per unit of enzyme activity. Immunoblots also indicated that the PDHC antigens were not different in normal and Alzheimer brains. This antibody, however, inhibited Alzheimer PDHC more effectively than it did control PDHC, based on milligrams of protein, suggesting a reduced amount of normal PDHC protein. Other data suggest that the PDHC deficiency is related to mitochondrial damage and to impaired calcium homeostasis in Alzheimer nerve cells, which may then mediate a variety of other cellular impairments.

Bone marrow function. I. Peripheral T cells are responsible for the increased auto-antiidiotype response of older mice

After immunization with trinitrophenyl (TNP)-Ficoll, mice produced both anti-TNP antibodies and auto-anti-idiotype (auto-anti-Id) antibodies specific for the anti-TNP antibody. Older animals produced more auto-anti-Id than did young animals. When mice were exposed to a normally lethal dose of irradiation while their bone marrow (BM) was partially shielded, they survived and slowly (6 wk) regained immune function, as indicated by the number of nucleated cells in their spleen and the in vitro primary plaque-forming cell (PFC) response of their spleen cells to TNP-treated aminoethylated polyacrylamide beads. Recovery is presumably the result of repopulation of the peripheral lymphoid system by cells originating in the BM. By enzyme-linked immunosorbent assay (ELISA), and by hapten-augmentable PFC assay, we show that, after recovery from irradiation with their BM shielded, old animals produce low auto-anti-Id responses, like those of young animals. The transfer of splenic T cells into mice irradiated with their BM shielded provided evidence that the magnitude of the auto-anti-Id response is controlled by the peripheral T cells. Thus, mice that received splenic T cells from aged donors produced high levels of auto-anti-Id while those that received splenic T cells from young donors produce low levels of auto-anti-Id.

Plaque-forming cell response of human blood lymphocytes. III. Cellular basis of the reduced immune response in the elderly

The cellular basis for the reduced immune response of the elderly was studied in vitro. It was found that, with respect to the capacity to respond to relatively T-independent B cell activators by proliferation and generation of plaque-forming cells (PFC), the purified B cell population of aged subjects is relatively intact. Furthermore, macrophages from old and young subjects produce T cell-replacing factors in equivalent amounts. The depressed proliferation and PFC responses to B cell activators in unfractionated lymphocytes from the elderly thus appear to be due to suppressor activity present in a surface Ig-negative cell population, suggesting that alterations in the regulatory (helper and suppressor) functions of T cell populations are the major cause of the reduced humoral immune response associated with aging.

Immunochemical characterization of pyruvate dehydrogenase complex in rat brain

Pyruvate dehydrogenase complex (PDHC) in rat brain was studied immunochemically, using antibodies against the bovine kidney PDHC, by immunoblotting, immunoprecipitation, inhibition of enzyme activity, and enzyme-linked immunoabsorbent assay (ELISA). The immunoblots showed that the antibodies bound strongly to the alpha peptide of the pyruvate dehydrogenase (E1) component, and to the dihydrolipoyl transacetylase (E2) and the dihydrolipoyl dehydrogenase (E3) components of PDHC. A similar immunoblotting pattern was observed in all eight brain regions examined. On immunoblotting of the subcellular fractions, these PDHC peptides were observed in mitochondria and synaptosomes but not in the postmitochondrial supernatants. This agrees with other evidence that brain PDHC is localized in the mitochondria. These results, together with those from sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the immunoprecipitin, also showed that the alpha E1, beta E1, and E3 peptides of rat brain PDHC are very similar in sizes to those of the bovine kidney PDHC, being 42, 36, and 58 kD, respectively. The size of the E2 peptide, 66 kD, is different from that of bovine kidney E2, 73 kD. The relative abundance of PDHC protein in nonsynaptic mitochondria was compared by enzyme activity titration and ELISA. Both methods demonstrated that the amount of PDHC antigen in the mitochondria from cerebral cortex is greater than that in the olfactory bulb mitochondria. This is consistent with the results of the activity measurement. The ELISA also showed that the PDHCs in both mitochondrial populations are antigenically similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the bovine brain pyruvate dehydrogenase complex using the antibodies against kidney enzyme complex

Pyruvate dehydrogenase complex (PDHC) was purified from bovine kidney with a specific activity of 12-16 mumol of NADH or acetyl-CoA formed/min/mg protein. The four peptides comprising its three catalytic components were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Rabbit antibodies against this highly purified PDHC (anti-PDHC) exhibited similar binding affinity to the phospho-PDHC as it did to the PDHC antigen. To test whether there exist brain isozymes of PDHC differing from kidney enzyme, which has been extensively characterized, the PDHCs in bovine brain and kidney were compared using this anti-PDHC. The PDHC activities in the brain and kidney mitochondrial extracts were inhibited to the same degree by varying amounts of anti-PDHC. Brain PDHC was precipitated with the anti-PDHC and resolved by SDS-PAGE. The four brain PDHC peptides isolated immunochemically with anti-PDHC had the same sizes as the kidney PDHC peptides. These PDHC peptides from kidney and brain were further compared by their peptide fragment patterns, which were generated by partial proteolysis with Staphylococcus aureus V8 protease or by CNBr and resolved by SDS-PAGE. The peptide patterns generated with the former method indicated that the alpha and beta peptides of the pyruvate dehydrogenase (E1) component and the peptide of dihydrolipoyl transacetylase (E2) component of kidney PDHC were very similar to the corresponding peptides immunologically isolated from brain. The peptide patterns generated with CNBr further confirmed that the beta E1 and E2 peptides of kidney PDHC were similar to the corresponding peptides from brain.

Effects of nutrition on disease and life span. I. Immune responses, cardiovascular pathology, and life span in MRL mice

Mice of the autoimmune, lymphoproliferative strain MRL/lpr and the congenic, nonlymphoproliferative strain MRL/n were fed one of six diets from weaning on-ward. These mice were sacrificed at 3 or 5 months of age. Low fat diets resulted in lower cholesterol and higher triglyceride levels than did cholesterol-containing high-fat diets. Caloric restriction of MRL/lpr mice was associated with an increased plaque-forming cell response to trinitrophenylated polyacrylamide beads, less lymphoproliferation, and less severe glomerulonephritis. Diet did not affect the incidence of autoimmune vasculitis in MRL/lpr mice sacrificed at 5 months. MRL/lpr mice fed a low-fat, calorically restricted diet from 5 months of age to death lived longer than mice which were fed ad libitum a cholesterol-containing, high-fat diet. At death, MRL/lpr mice fed the former diet had the autoimmune vasculitis which had been evident in mice killed at 5 months, whereas mice fed the latter diet, in addition to the vasculitis, had a high incidence of atherosclerotic lesions of intrarenal and aortic branch arteries.

Immunologic studies on the induction of diabetes in experimental animals. Cellular basis for the induction of diabetes by streptozotocin

Repeated low doses of streptozotocin (STZ, 40 mg/kg body wt) gradually induce hyperglycemia in mice after a latent period of 5-7 days. The ability of STZ to induce hyperglycemia varies in different mouse strains. Repeated low doses of STZ fail to induce diabetes in T-cell-deficient mice, suggesting a crucial role of T-cells in the induction of diabetes by this procedure. Transfer of spleen cells from mice rendered diabetic by repeated low doses of STZ failed to induce hyperglycemia in the recipients. However, pretreating the recipients with a single low dose of STZ permitted efficient transfer of the diabetic state, suggesting that the immunologic reaction resulting in diabetes was actually specific for an STZ-modified beta cell.

Cefoperazone (Cefobid) for treating men with gonorrhoea caused by penicillinase producing Neisseria gonorrhoeae

The recent emergence of spectinomycin resistant penicillinase producing Neisseria gonorrhoeae (PPNG) and the high prevalence of PPNG strains among the gonococcal isolates in Seoul represent a grave challenge to the programme for controlling sexually transmitted disease (STD). Fifty men with uncomplicated gonococcal urethritis caused by PPNG strains were treated with a single intramuscular injection of 1 g cefoperazone. Forty two patients were followed up. All patients recovered including three who became reinfected and required further treatment. Two patients (4.8%) developed postgonococcal urethritis (PGU). The MIC90 of cefoperazone measured by an agar dilution susceptibility test was 0.12 mg/l.

Induction of insulin-dependent diabetes by streptozotocin. Inhibition by estrogens and potentiation by androgens

Susceptibility of mice to experimental insulin-dependent diabetes as induced by multiple subdiabetogenic doses of streptozotocin has been shown to be strongly gender-dependent, males being much more susceptible than females. We examined this gender difference further in two strains of genetically susceptible mice to determine whether exogenous steroid sex hormones can both suppress the high susceptibility of males and potentiate the low susceptibility of females. Our results show that, in both BALB/cBOM and C57BL/6 mice, exogenous estrogens can suppress the high susceptibility of males. Conversely, the normally streptozotocin-resistant females become as highly susceptible as males after the administration of androgens. The inhibitory effect of estrogens and the potentiating effect of androgens can be demonstrated after the hormones are given to the mice either chronically (in slow-release capsules implanted at a subcutaneous site), or immediately prior to streptozotocin injection. These observations are consistent with the view that the critical factor that determines the susceptibility of mice to the hyperglycemic effects of streptozotocin is not the absolute concentration of androgens per se, but rather the relative overall level of androgens over estrogens in the recipient animal. Several alternative mechanisms for the effect of sex hormones on diabetogenic sensitivity are discussed.

Regulation of immune response in allogeneic mixed spleen cell cultures. I. Influence of I-region on the generation of suppressor cells

The immune responses of allogeneic mixed spleen cell cultures (MLC) to the T-dependent antigen, SRBC, and to the T-independent antigen, DNP-PAA, were investigated. The immune response to DNP-PAA in MLC with certain strain combinations was always suppressed as compared with the expected PFC response calculated from the PFC responses of the individual strains. This suppression was eliminated by treating the spleen cells with RAMB antiserum plus complement before the incubation of the MLC with DNP-PAA. It can be concluded that the suppression in the PFC response to the T-independent antigen DNP-PAA in MLC is due to the generation of suppressor T-cells. The PFC response to the T-dependent antigen, SRBC, in MLC showed either suppression, no change, or rarely augmenation, suggesting that the allogeneic mixed spleen cell cultures can generate both suppressor and helper T cells and that the balance between helper and suppressor activity regulates the PFC response to a T-dependent antigen. Suppressor activity was also generated in a one-way MLC, but the degree of suppression depended upon which of the two strains was responding. Similar amounts of thymidine were incorporated in the one-way MLR irrespective of which strains was responding. Thus, the extent of proliferation in one-way MLR is not related to the degree of suppressor activity generated. The results further indicate that a difference between two strains in the I-C, S, and G regions of the major histocompatibility complex is required to generate suppressor activitiy that can depress the response to a T-independent antigen, MLC between strains differing in K, I-A, I-B, I-J, I-E, and D regions generate little or no suppressor activity in this system.

Regulation of immune response in allogeneic mixed spleen cell cultures. I. Influence of I-region on the generation of suppressor cells

The immune responses of allogeneic mixed spleen cell cultures (MLC) to the T-dependent antigen, SRBC, and to the T-independent antigen, DNP-PAA, were investigated. The immune response to DNP-PAA in MLC with certain strain combinations was always suppressed as compared with the expected PFC response calculated from the PFC responses of the individual strains. This suppression was eliminated by treating the spleen cells with RAMB antiserum plus complement before the incubation of the MLC with DNP-PAA. It can be concluded that the suppression in the PFC response to the T-independent antigen DNP-PAA in MLC is due to the generation of suppressor T-cells. The PFC response to the T-dependent antigen, SRBC, in MLC showed either suppression, no change, or rarely augmenation, suggesting that the allogeneic mixed spleen cell cultures can generate both suppressor and helper T cells and that the balance between helper and suppressor activity regulates the PFC response to a T-dependent antigen. Suppressor activity was also generated in a one-way MLC, but the degree of suppression depended upon which of the two strains was responding. Similar amounts of thymidine were incorporated in the one-way MLR irrespective of which strains was responding. Thus, the extent of proliferation in one-way MLR is not related to the degree of suppressor activity generated. The results further indicate that a difference between two strains in the I-C, S, and G regions of the major histocompatibility complex is required to generate suppressor activitiy that can depress the response to a T-independent antigen, MLC between strains differing in K, I-A, I-B, I-J, I-E, and D regions generate little or no suppressor activity in this system.

Induction of suppressor activity in the autologous mixed lymphocyte reaction and in cultures with concanavalin A

T lymphocytes that are activated in the autologous mixed lymphocyte reaction (MLR) have suppressor activity. Concanavalin A (Con A) augments the suppressor activity generated in cultures containing both T and non-T lymphocytes and can induce suppressor activity in T-lymphocyte preparations that contain too few (10%) non-T cells to generate a significant autologous MLR. However, when such T-lymphocyte preparations are further depleted of adherent cells and contain less than 2% non-T cells, Con A fails to induce suppressor activity. These findings support the concept that an autologous MLR may play an important role in generation of suppressor cells by Con A.

Hyperglycemic factor in submandibular glands and its etiological relations to diabetes mellitus in mice

Bilateral ligation of both the submandibular and parotid ducts of adult normal and mutant hyperinsulinemic diabetic mice resulted in a significant hypoglycemic effect. Therefore, we postulated that duct ligation may result in the removal of hyperglycemic factor (Hoshino et al., 1976) rather than a change in insulin sensitivity. Indeed, no change in specific binding of 125I-insulin was observed in membrane fractions from several tissues obtained from mice of either sex or strains before and after duct ligation. After slices of the submandibular gland were incubated for 4 hr in Eagle's medium, an aliquot of the culture medium was injected i.p. into normal adult mice. A signigicant hyperglycemic effect was observed in 30 min in the injected animals. Eluates obtained by gel filtration of the crude extract of the submandibular gland were injected into normal adult mice, and hyperglycemia ensued. Thus, it is postulated that ligation of salivary ducts results in glandular atrophy and disappearance of the hyperglycemic factor which in turn leads to hypoglycemia and amelioration of diabetes mellitus, particularly of hyperinsulinemic type.

Modification of radiation-induced pulmonary fibrosis in rats

Male rats received 25 Gy (2,500 rad) of gamma rays to the right hemithorax and were killed three or six months later. Microscopic pulmonary abnormalities developed sooner and progressed more rapidly in animals given control feed than in those given the collagen antagonist D-penicillamine (10 mg/day, p.o.). Three and four months after irradiation, hypoperfusion and radiographic hyperlucency of the right lung were observed in both the treated and control animals.

Cellular basis for a hapten-specific state of tolerance induced in vitro

A hapten-specific unresponsive state was induced in vitro by the incubation of normal murine spleen cells with highly conjugated dinitrophenylated bovine gamma-globulin (DNP-BGG) or a dinitrophenylated copolymer of D-glutamic acid and D-lysine (DNP-D-GL) for 24 hr. After this incubation period spleen cells were washed and cultured for 4 days with the thymic-independent antigen dinitrophenylated polyacrylamide beads (DNP-PAA) or the thymic-dependent antigen trinitrophenylated burro the erythrocytes (TNP-BRBC). Preincubation with either DNP-BGG or DNP-D-GL led to a specific depression of the in vitro anti-hapten plaque-forming cell response. The degree of depression was dependent upon the concentration of the tolerogen and the duration of preincubation. The response to DNP-PAA or TNP-PAA beads was depressed to a greater degree than was the response to TNP-BRBC. The cellular basis of the immunologic unresponsiveness induced by DNP-BGG was attributable to an inhibition of B cell function whereas the unresponsive state induced with DNP-D-GL was due to both a specific inhibition of B cell function and the activation of antigen-specific suppressor T cells.

Studies on the control of antibody synthesis. XII. Genetic influences on antibody affinity

Genetic controls on the concentration and affinity of the anti-dinitrophenyl antibodies produced by different inbred strains of mice in response to immunization with dinitrophenylated bovine gamma globulin in Freund's complete adjuvant were demonstrated. Based upon data on F1 hybrids and backcrosses, it can be concluded that there are genetic controls on antibody affinity which are not linked to the major histocompatibility complex. In addition, the genetic controls on affinity which were studied here appear to be inherited independently of genetic controls on antibody concentration.

Species and strain differences in the lethal factor of the mouse submandibular gland

The differences in susceptibility of animals to the lethal factor extracted from the mouse submandibular gland and magnitude of its lethality were compared among various species, strains, ages, and sex of mice. Comparisons of LD50 values computed by an IBM 360/System computer using a programmed probit analysis yielded the following significant results. The lethal factor of adult male mice was lethal to all species and strains of animals tested. Strain differences were observed in five inbred strains of mice, and varying degrees of resistance against the lethal factor were demonstrated. The lethality was strongest in the submandibular gland of our subline BALB/c mice, and the highest susceptibility to the lethal factor was demonstrated by female C57BL mice. This factor was found to be lethal not only to mice but also to other species of animals, Mongolian gerbils being most susceptible and New Zealand rabbits next.

Detection of virus-specific antibody-forming cells of mice immunized with Newcastle disease virus

The hemolytic plaque assay was adapted to the detection of antibodies to Newcastle disease virus (NDV) in an in vivo, an in vitro system, and a combined in vivo-in vitro system. Several conditions were tested for coupling of sheep erythrocytes to NDV and for the kinetics of plaque formation in the in vivo and in vitro systems. The one set of conditions which provided the best responses is presented. The effect of multiple injections of NDV into mice on plaque formation was optimized.

A comparison of the Farr technique with equilibrium dialysis for measurement of antibody concentration and affinity

The Farr technique has been compared with equilibrium dialysis in regard to its ability to measure antibody concentration and affinity. An excellent qualitative agreement between the two techniques was obtained. Quantitatively, the Farr technique tended to underestimate antibody concentration and overestimate antibody affinity. It is likely that these observations are due to the failure of some low affinity antibodies to bind hapten under the conditions of the Farr assay.

Studies on the control of antibody synthesis. VI. Effect of antigen dose and time after immunization on antibody affinity and heterogeneity in the mouse

The effect of antigen dose and time after immunization on the affinity of serum antihapten antibody was studied in the mouse by the Farr technique and by equilibrium dialysis. A progressive increase in affinity was seen with time after immunization at all antigen dose levels. The rate of increase in affinity was faster with lower doses of antigen. However, the increase in affinity continued for a longer time in animals immunization with larger doses of antigen. Consequently, at 3 months after immunization animals injected with a larger dose of antigen had higher average affinity antibody than did animals immunized with low doses of antigen. Low affinity antibody was produced in significant amounts at all immunizing dose levels and was present throughout the course of the immune response. Certain technical problems in interpretation of equilibrium dialysis data are discussed.

Studies on antigenic competition. 3. Effect on antigenic competition on antibody affinity

The effect of antigenic competition on antibody affinity was studied using a haptenic system in guinea-pigs. A moderate depression in the amount of antibody formed, as a result of antigenic competition, had relatively little effect on affinity. Increasing the dose of the competing antigen resulted in a greater degree of competition. Under these conditions a large amount of low affinity antibody was produced by the animals while essentially no high affinity antibody was detectable. Thus, marked competition appeared to result in a failure to select for high affinity antibody synthesis.

The generation of antibody diversity. I. Studies on the population distribution of anti-DNP antibody affinities and on the influence of allotype on antibody affinity and concentration

A genetically diverse population of sixty-four rabbits has been studied with respect to the concentration and affinity of anti-DNP antibody produced over the course of a year following a single injection of DNP-BGG. It was found that the responses of male and female members of the population were essentially identical throughout the entire course of the immune response. The effect of allotype on the concentration and affinity of the antibody produced was examined. It was observed that the b6 allotype was associated with the production of decreased concentrations of antibody, the b5 allotype with the production of increased concentrations of antibody, the a1 allotype with the production of high affinity antibody and the a2 allotype with the production of low affinity antibody when compared to the remainder of the population. A tendency was also seen for individuals to maintain, over the course of time, their relative position in the population with respect to the concentration and affinity of the antibody they produce. Finally, it was observed that the mean affinity of the population continually shifted towards high affinity over the period of observation and that the standard deviation of the population with regard to the affinity of the antibody produced decreased with time.

Studies on the control of antibody synthesis. 3. Changes in heterogeneity of antibody affinity during the course of the immune response

The distribution and heterogeneity of antibody affinity has been followed with time after immunization. Initially, a symmetrical distribution of heterogeneous low affinity antibody molecules is present. With time the population becomes skewed towards the high affinity end of the distribution, the average affinity increases, and the bulk of the antibody generally comes to be present in a subpopulation of high affinity and of relatively restricted heterogeneity. Still later after immunization, the proportion of high affinity antibody decreases and a highly heterogeneous population of antibody molecules is present with a somewhat decreased average affinity. Low affinity subpopulations were found to persist throughout the course of the immune response. In addition it was noted that by day 42 after immunization a significant amount of the highest affinity antibody that a given rabbit would synthesize at any time during its immune response was already present. Thus, changes in average affinity can be accounted for by shifts in the relative amounts of those antibody subpopulations already present by day 42 and do not require the appearance of any new antibody species. The results can be interpreted as consistent with a selection theory of antibody synthesis in which cells of high affinity are preferentially selected in what amounts to a micro-evolutionary system.