Unusual phenotype of B cells in the thymus of normal mice

A small number of B cells are found in the thymus of normal mice. A population of B lymphocytes could be enriched to greater than 90% purity by isolating a low-density fraction on Percoll density gradients and then depleting T cells with a mixture of anti-Thy-1, CD4, and CD8 mAbs and complement. Enrichment was monitored by surface Ig staining and by functional studies (responsiveness to LPS, and to anti-mu plus IL-4). When the phenotype of these B cells was studied by flow cytometry, 60-80% had the phenotype Ly-1+ (CD5), Ia+, B220low (CD45R), and Mac-1+ (CD 11b). In contrast, splenic B cells lacked CD5 and CD11b and expressed higher levels of B220 and Ia antigens. These results indicate that most thymic B cells have the phenotype of the Ly-1 B cell subset, which was identified previously as a trace subpopulation in some peripheral tissues and is thought to play a role in autoantibody formation.

Reactivities of 4 murine coronavirus antigens with immunized or naturally infected rat sera by enzyme linked immunosorbent assay

Four murine coronavirus antigens, sialodacryoadenitis virus (SDAV) strain TG, Parker's rat coronavirus (PCV) strain 8190, mouse hepatitis virus (MHV) strains S and NuU, were examined for their reactivities to hyperimmunized and naturally infected rat sera by ELISA. With the immunized sera, SDAV and PCV antigens reacted best with respective homologous sera. MHV antigens reacted with all antisera, anti-SDAV, anti-PCV, and anti-MHV-S at approximately the same level, and MHV-S showed a slightly higher reactivity than MHV-NuU. The reactivities of the sera from various colonies to these antigens were in the order--from high to low--of SDAV, MHV-S, MHV-NuU, and PCV. None of sera negative for SDAV antigen reacted positively to the other antigens. Within the sera positive for SDAV, the positivities were in the order of MHV-S, MHV-NuU, and PCV. These results suggested that, although homologous antigens are best to detect SDAV or PCV infection by ELISA, MHV antigen can be used if highly cross-reactive viral strain is selected.

T cells subsets responsible for clearance of Sendai virus from infected mouse lungs

T cell subsets responsible for clearance of Sendai virus from mouse lungs determined by adoptive transfer of immune spleen cell fractions to infected nude mice. T cells with antiviral activity developed in spleens by 7 days after intranasal infection. Spleen cell fractions depleted of Lyt-2+, Lyt-1+, or L3T4+ cells showed antiviral activity in vivo, although the degree of the activity was lower than that of control whole spleen cells. The antiviral activity of the Lyt-2+ cell-depleted fraction was consistently higher than that of L3T4+ (Lyt-1+)-depleted cells. In vitro cytotoxic activity against Sendai virus-associated, syngeneic lipopolysaccharide-blast cells was detected in stimulated cells from intraperitoneally immunized mice but was lost after depletion of Lyt-2+ cells. Multiple injection of anti-Sendai virus antibody into infected nude mice had no effect on lung virus titer. These results indicate that L3T4+ (Lyt-1+) and Lyt-2+ subsets are cooperatively responsible for efficient clearance of Sendai virus from the mouse lung.

Variation of virulence and other properties among Sendai virus strains

The virulence of five Sendai virus strains (MN, Z, KN, Mol, and Hm) isolated from laboratory rodents was compared, using 3-week-old female Jcl-ICR mice. The virulence of the strains was Mol, MN, KN, Z, and Hm in decreasing order. The 50% lethal dose and 50% lung consolidation inducing dose of the highest virulent strain differed by the order of more than 10(3) and 10(6), respectively, from those of the lowest virulent one. Other properties such as the growth rate in LLC-MK2 cells, neuraminidase activities, and molecular weights of structural proteins also differed among the virus strains. These results indicate that Sendai virus prevailing in laboratory rodents is not homogenous with respect to virulence and some other properties.

Successful pancreatic allografts in combination with bone marrow transplantation in mice

We have established a new method for pancreatic allografts in mice by combining pancreatic transplantation with allogeneic bone marrow transplantation. In this approach, we first transplanted bone marrow to induce tolerance to both donor-type and host-type major histocompatibility complex (MHC) determinants. Pancreatic tissue from the same mouse strain as bone marrow donor was then grafted under the renal capsule. Acceptance of the grafts was confirmed by histopathological and immunohistochemical techniques. BALB/c mice reconstituted with C57BL/6J bone marrow cells accepted pancreatic tissue from both bone marrow donor (C57BL/6J)-type and host (BALB/c)-type mice. An immunohistochemical study revealed the presence of functional islets under the renal capsules. Assays for both mixed lymphocyte reaction (MLR) and induction of cytotoxic T lymphocytes indicated that the newly developed T cells are tolerant of both donor (stem cell)-type and host-type MHC determinants. By contrast, the T cells of these chimeras showed a significant responsiveness to third party MHC determinants. These findings suggest that pancreatic allografts combined with bone marrow transplantation may become a viable strategy for the treatment of patients with diabetes or patients who have undergone pancreatectomy.

Treatment of type 1 diabetes mellitus in non-obese diabetic mice by transplantation of allogeneic bone marrow and pancreatic tissue

Non-obese diabetic (NOD) mice provide a model for type 1 diabetes mellitus. We previously showed that allogeneic bone marrow transplantation (ABMT) can prevent and treat insulitis and overt diabetes in NOD mice. However, ABMT alone could not be used to treat overt diabetes in NOD mice whose islets had been completely destroyed. To provide insulin-producing cells, pancreatic tissue from newborn mice was grafted under the renal capsules in combination with ABMT. The aims of concomitant ABMT are as follows. (i) It induces immunological tolerance to the donor-type major histocompatibility complex determinants and permits the host to accept subsequent pancreatic allografts from the bone marrow donor. (ii) ABMT replaces abnormal stem cells with normal stem cells. After transplantation of bone marrow plus newborn pancreas, NOD mice showed reduction of the glycosuria and a normal response in the glucose-tolerance test. Immunohistological study revealed the presence of clustered insulin-containing beta cells in the grafted pancreatic transplants. ABMT may become a viable treatment of established type 1 diabetes mellitus in humans.

Prevalence of antibodies to Sendai virus and rotavirus in laboratory rabbits

One hundred and sixty rabbit sera from 10 breeding colonies and 13 laboratory colonies were tested for antibodies to Sendai virus and rotavirus by enzyme-linked immunosorbent assay (ELISA). Antibodies were detected to Sendai virus in 53% and to rotavirus in 81%, indicating the prevalence of these viral infections in laboratory rabbit colonies.

Spontaneous arthritis in nude rats of Rowett hooded strain

Spontaneous arthritis was found in 19 of 55 Rowett hooded strain rats with rnu gene. Most cases were in the male rnu/rnu (15/19) but a few occurred in the male rnu/+ (3/10) and female rnu/rnu (1/8). The lesions were first noted as reddened swelling due to exudative inflammation of periarticular soft tissues including synovial membranes in the tarsal and/or carpal joints. Most of the affected animals cured leaving slight induration but in a few male rnu/rnu ankylosis with pannus formation and exostosis developed. No sign of mycoplasmal or bacterial infection was noticed in the colony.

[Effect of diuretic, azosemide (SK-110), in combination with antibiotic, cephaloridine, on kidney]

This study was performed to compare the acute-renal toxicity of azosemide (SK-110) or furosemide (FM) treatment in combination with cephaloridine (CER). 1) Initially, the acute-renal toxicity of CER was studied after a subcutaneous administration at dose levels of 500, 1000, 1500 and 2000 mg/kg. The values of BUN, creatinine and relative kidney weights were increased in rats given CER at dose levels above 1500 mg/kg. consequently, it was considered that the threshold of CER with regard to acute-renal toxicity was 1000 mg/kg. 2) Secondarily, the acute-renal toxicity of SK-110 or FM were studied after oral administration of 40, 80, 160 or 320 mg/kg doses alone or in combination with CER. Acute-renal toxicity was evident in the 320 mg/kg-treated rats after both SK-110 and FM alone, as revealed by analysis of a number of parameters, i.e., BUN, serum creatinine, urine sediment and composition and pathological data composing both kidney weights and studies at the microscope level. However, the increase of BUN and relative kidney weights values, elevated numbers of epithelial cells in the urine and necrosis observed in the uriniferous-tubular epithelium on histopathological examination of kidneys were noted in rats given at dose levels of only 80 mg/kg with SK-110 + CER, whereas they were seen in animals treated with FM even at the lowest applied dose of 40 mg/kg in combination with CER. In conclusion, this study showed that the minimum dose of SK-110 or FM in combination with CER which causes acute-renal toxicity were, respectively, 80 mg/kg or less than 40 mg/kg.

Immunoglobulin classes of anti-Sendai virus antibody detected by ELISA in infected nude mouse serum

Sendai virus-infected nude mouse sera obtained on the seventh day after infection or later, in which anti-Sendai virus antibodies were undetectable by hemagglutination-inhibition and neutralization tests, were found to be reactive with the virus antigen by ELISA using horseradish peroxidase-conjugated anti-mouse IgG rabbit IgG. The reactivity was blocked by rabbit anti-Sendai virus antiserum and was not observed against influenza virus which served as a control antigen. Anti-Sendai virus antibody activity of fractions from Sephadex G-200 gel filtration was detected in the IgM fraction when anti-mouse mu chain-specific antiserum was used and in both IgG and IgM fractions when heavy and light chain-specific anti-mouse IgG serum was employed in ELISA. ELISA of the fractions from protein A-Sepharose affinity chromatography of Sendai virus-infected nude mouse sera showed that the eluates at pH 6.0 and pH 3.5 contained IgG1 and IgG2b anti-Sendai virus anti-bodies, respectively, and that the eluate at pH 4.5 contained both IgG2a and IgG3 antibodies.

[Effect of triphenyltin chloride on superoxide (O2-.) production in human neutrophils]

Brief treatment (3 min at 37 degrees C) of human neutrophils with triphenyltin chloride (TPTC1) resulted in a dose-dependent inhibition of superoxide (O2-.) production stimulated by concanavalin A+ cytochalasin D. It was considered from the following findings that the inhibition may be caused by some functional disorders of neutrophils: 1) O2-. generated by xanthine oxidase-acetaldehyde system was not inhibited by TPTC1. 2) There was no change in cell viability after treatment with TPTC1. When the other phenyltin compounds were examined, the relative potencies of inhibitory effect were shown to be in the order of TPTC1 greater than diphenyltin dichloride greater than phenyltin trichloride greater than tetraphenyltin on a molar basis. Lysosomal enzyme release caused by neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (FMLP) was also inhibited by TPTC1. These results suggest that TPTC1 inhibits the common pathway(s) of the two stimulus responses.

[Experimental induction of atherosclerosis in guinea pigs fed a cholesterol and vitamin D2-rich diet]

Atherosclerotic lesions of aorta and arteries were induced in guinea pigs fed a diet supplemented with 1% cholesterol and vitamin D2 (0.75 million IU/kg of diet) for 6 weeks. Histopathological observation revealed intimal proliferation and calcification of the intima and media, but no atheroma was present at the sites of arterial injury. However, the biochemical findings revealed accumulation of cholesterol, mainly esterified, and calcium in the aorta. Significant correlation between the calcium and phosphorus contents in the aorta indicates the presence of a probable calcium-phosphate complex. Synergism for the induction of atherosclerotic lesions was shown between high cholesterol and excess vitamin D2. Sodium 4-(hexadecylamino)benzoate (cetaben) (90 mg/kg/day, p.o.) and trisodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) (5 mg/kg/day, s.c.) inhibited the development of atherosclerotic lesions induced in this manner. These effects were associated with a significant reduction of serum and aortic cholesterol levels and a significant elevation of HDL-cholesterol levels caused by cetaben, and a significant reduction in aortic calcium caused by EHDP. These two drugs and clofibrate, however, had no significant effect on the regression of pre-established atherosclerotic lesions.

Hypoglycemic activity of 1-alpha-(3,4-dimethoxyphenethylaminomethyl) -2-hydroxybenzylalcohol 1/2 fumarate (TA-078) in the mouse, rat and dog

1-alpha-(3,4-Dimethoxyphenethylaminomethyl)-2-hydroxybenzylalcohol 1/2 fumarate (TA-078) is a new hypoglycemic agent structurally different from any existing hypoglycemic drug. It depresses the rise of blood glucose when it is orally administered to glucose-loaded mice, rats and beagle dogs at minimal doses of 1, 10 and 2.5 mg/kg, respectively. In contrast with tolbutamide, TA-078 hardly affected fasting blood glucose levels in rats and dogs and only weakly reduced fasting blood glucose levels in mice. Oral administration of TA-078 to KK mice also improved glucose tolerance, while no improvement was observed in streptozotocin-diabetic rats. TA-078 elevated plasma immunoreactive insulin (IRI) levels in mice and rats soon after its oral administration. In fasted rats, TA-078 caused only a transient increase in plasma IRI but did not affect plasma immunoreactive glucagon (IRG) levels in the early phase after its administration. On the other hand, tolbutamide induced a sustained increase in plasma IRI and a transient but marked decrease in plasma IRG. In perfused rat pancreas, TA-078 stimulated insulin secretion. The stimulation by 10 micrograms/ml TA-078 in the perfusion liquid required the presence of a normal concn (5.6 mM) of glucose, whereas the same concn of tolbutamide stimulated insulin release even at a low glucose concn (2.8 mM).