The delayed-type hypersensitivity (DTH) to Japanese encephalitis virus (JEV) and the suppressor cells controlling it and the antibody-forming cells in inbred Swiss mice have been studied. JEV induces DTH, with a peak response at day 7 following infection which persists at low levels at least up to 119 days. Suppressor activity appeared on day 18. It was transferable by immune spleen cells. Treatment of spleen cells with anti-Thy-1.2 antisera and complement abrogated the suppressor activity. The homogenate of the spleen was equally effective in mediating suppression of DTH and the humoral response as measured by direct antibody plaque-forming cell (IgM-PFC) assay. The suppressor activity was antigen-specific both on DTH and T helper for antibody response as the immune responses against SRBC or Coxsackie B4 virus were not suppressed. The suppressor cells were sensitive to cyclophosphamide treatment when the drug was given 48 hr before their appearance. It is, therefore, concluded that in JEV infection of mice, antigen-specific suppressor T cells are generated, both for DTH and IgM antibody, which are cyclophosphamide-sensitive and mediate suppression through soluble product(s).

Animals↗

PubMed1984

Status of zinc in pulmonary tuberculosis.

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Female↗

PubMed1984

Effect of dengue virus-induced macrophage cytotoxin on functions of human blood leucocytes.

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Cytotoxins↗

PubMed1984

Effect of dengue virus-induced cytotoxic factor on Fc-receptor functions of mouse macrophages.

Many defects in macrophage functions in dengue type 2 virus (DV) infection have been shown to be mediated by production of the virus-induced cytotoxic factor (CF). An attempt has been made to determine whether the alterations in Fc-mediated functions of macrophages in DV-infected mice are due to CF. Mice given CF intravenously show a rapid fall in total numbers of peritoneal and spleen cells. The number of cells in the peritoneal cavity recovered in 48 h. but recovery in the spleen was not significant. The capacity of the splenic and peritoneal macrophages to attach and ingest opsonized sheep erythrocytes was significantly reduced, the lowest values of attachment index (AI) and phagocytic index (PI) being observed within 2-3 h. At later periods the AI values increased markedly but the PI values remained depressed. The effect was dose-dependent. The effect on Fc-receptor functions of macrophages in DV-infected mice thus appears to be mediated through CF.

Animals↗

PubMed1983

Effect of dengue virus infection on Fc-receptor functions of mouse macrophages.

Fc-receptor-mediated attachment and ingestion of opsonized sheep erythrocytes (EA) by the macrophages of spleen and peritoneal cavity were studied during dengue virus type 2 (DV) infection of Swiss albino mice. Following intracerebral inoculation, virus antigen could be demonstrated by immunofluorescence in the splenic macrophages from day 4 and in peritoneal macrophages from day 5 post-infection, with a higher number of positive cells discernible on the 7th and 8th days. The virus could be isolated from spleen tissue from day 5. The total number of cells was markedly reduced from day 4 onwards both in the spleen and peritoneal cavity. A loss in the capacity to attach and ingest EA was noticed, the lowest values of attachment index (AI) and phagocytic index (PI) being reached on day 4. At later periods the AI values increased markedly but continued to be significantly less than those in uninfected control mice. The PI values continued to be lower throughout. The dichotomy between the Fc-mediated attachment and ingestion may be a mechanism for prevention of virus infection of macrophages.

Animals↗

PubMed1983

Host defence mechanisms against Japanese encephalitis virus infection in mice.

The role of antibody and cell-mediated immunity in the resistance to Japanese encephalitis virus (JEV) infection was studied in adult mice. Passively transferred antibodies obtained up to 2 weeks after primary infection protected the recipient mice against a challenge infection with JEV. Antibody obtained at 4 or 5 weeks failed to protect despite the presence of high titres of neutralizing antibody. Protection was abrogated by pretreatment of the early serum with 2-mercaptoethanol to remove IgM. Similarly, adoptive transfer of immune spleen cells obtained up to 2 weeks after immunization provided protection. The protective effect was abolished by pretreatment of the immune spleen cells with anti-Thy 1.2 antiserum and complement. These findings suggest a role of T lymphocytes and IgM antibody in recovery from JEV infection.

Animals↗

PubMed1983

Immune response to Japanese Encephalitis virus in mother mice and their congenitally infected offspring.

The immune response to Japanese encephalitis virus (JEV) was assessed in JEV-infected mice (mothers) and their offspring. The congenitally infected baby mice responded poorly in all assays for cell-mediated immunity. The total number of their splenic cells remained unaltered but the percentage of T cells was significantly reduced; a depressed delayed hypersensitivity response was seen against both homologous (JEV) and heterologous (sheep erythrocytes) antigens. In addition, significantly higher leukocyte migration inhibition (LMI) of spleen cells in the presence of specific antigen was observed. Adult mice infected during pregnancy demonstrated an impaired delayed hypersensitivity response to JEV antigen only. LMI was positive in mothers at 2 weeks post-partum, but not at later periods.

Animals↗

PubMed1983

Zinc, copper, magnesium, and calcium in blood and plasma after phlebotomy.

Zinc levels in plasma and whole blood were investigated in 2 groups of blood donors. The first group consisted of 19 men and 11 women who donated blood for the first time and were followed during 3 phlebotomies. The second group comprised 44 men with 9 or more previous blood donations, their blood being analysed on a single occasion. Plasma concentrations of copper, magnesium, calcium and ferritin were also analysed. The zinc levels in whole blood and plasma in the second group were significantly lower as compared to the first group (P less than 0.001). Furthermore, the second group had significantly higher levels of copper and copper:zinc quotient in plasma as compared to those of the new blood donors (P less than 0.001). Our results indicate that besides the earlier known effect of blood donation on iron stores, there are also signs of zinc depletion when judged from the zinc levels in plasma and in erythrocytes. No significant changes in calcium and magnesium concentrations were seen during phlebotomy.

Adolescent↗

PubMed1983

Induction of suppressor cells in Japanese encephalitis virus infected mice.

Adoptive transfer of spleen cells obtained from mice primed with Japanese encephalitis virus (JEV) suppressed IgM antibody plaque forming cells (PFC) against JEV in the spleen. Similar suppression of PFC was also shown in vitro by adding primed spleen cells to JEV-stimulated spleen cell cultures. The suppressor activity appeared sharply in the third week after priming and persisted up to 6 weeks. By using various cell separation procedures it was found that the suppressor activity resided in the T cell enriched fraction and not in B cells or macrophages. Sensitivity of the cells to treatment with anti-Thy 1.2 antiserum and complement confirmed that suppressor cells were T lymphocytes. It was noted that the suppression was effective against dengue virus antigen also. Our findings thus show generation of suppressor T lymphocytes in JEV-infected mice.

Animals↗

PubMed1983

A scanning electron microscopy evaluation of peripheral nerve regeneration.

Regeneration of a transected peripheral nerve following repair is often impeded by scar formation and misdirection of axon sprouts. This paper describes the use of the scanning electron microscope (SEM) in conjunction with other physiologic tests to evaluate nerve regeneration. A central one centimeter segment was removed from the peroneal branch of both sciatic nerves in 37 white New Zealand rabbits. Sectioned nerves were divided into four experimental groups according to type of repair performed: (A) no repair; (B) mobilization and direct epineural repair; (C) interpositional nerve graft repair; (D) polyglycolic acid (PGA) conduit repair. Each animal was reexplored eight months later and nerves examined by electrophysiologic testing and scanning electron microscopy. Unrepaired nerves viewed by SEM showed impaired axonal regeneration and loss of fascicular morphology with increased scar tissue. Nerve sections of direct epineural and interpositional graft repairs showed the best return of axonal morphology. Nerves regenerated across a one centimeter gap through a PGA conduit demonstrated regrowth of small and large myelinated axons grouped into "mini-fascicles" with increased connective tissue. PGA conduit repairs were electrically inferior to graft and direct repairs as measured by conduction velocity and the amplitude of evoked response. These findings correlated well with anatomy seen on scanning electron micrographs. The scanning electron microscope proved an excellent adjunctive tool for the study of peripheral nerve regeneration.

Animals↗