Optimal culture conditions for in vitro antigen-induced proliferation of rat lymph node cells.

Popliteal and inguinal lymph node cells (LNC) from rats immunized with ovalbumin (OA) in Freund's adjuvant, were cultured with OA for 4 days in a variety of serum-supplemented media. Incorporation of [3H]thymidine into [3H]DNA was assessed as an index of antigen-induced lymphoproliferation. Optimal conditions for proliferation were found to comprise culture in flat-bottomed vessels, in the presence of RPMI 1640 medium adjusted to rat osmolality (310 mosmoles/kg) containing 5% v/v fresh syngeneic rat serum plus 4 X 10(-4) M 2-mercaptoethanol.

Radiation-resistant IgE-secreting cells in the mouse: susceptibility to suppressor T cells.

X-irradiation (800 or 1,000 R) of Balb/c mice displaying 'persistent' high-titer anti-ovalbumin IgE responses resulted in only minor decreases in antibody titres measured 40 days later, indicating that the bulk of IgE production could be ascribed to long-lived radiation-resistant (and thus non-dividing) plasma cells. IgE-specific suppressor T cells from ovalbumin-tolerant mice did not affect ongoing persistent IgE synthesis by these plasma cells, but prevented their emergence in ovalbumin-immunized mice and in those adoptively immunized with splenocytes from animals displaying persistent IgE responses.

Alveolar macrophages: antigen presentation activity in vivo.

Previous studies on the antigen-presenting activity of alveolar macrophages (AM) have been restricted to the use of in vitro assay systems, and have generally shown suppression of T cell activation by these macrophages. The present study exploits the rapid adaptability of AM to changes in oxygen tension, which facilitates their transfer to other tissues in a functional state. Employing this rationale, antigen-pulsed AM were shown to trigger T cell-dependent immune responses following subcutaneous or intraperitoneal inoculation, while suppressing similar responses in tissue culture.

Tolerance induction via antigen inhalation: isotype specificity, stability, and involvement of suppressor T cells.

Mice were exposed to aerosolized ovalbumin (OA) once weekly for 5 min on 6 occasions, prior to systemic challenge with soluble or alum-adsorbed (AH-OA) antigen. Mice challenged with AH-OA manifested profound IgE isotype-specific tolerance; those challenged with soluble OA initially manifested anamnestic IgE/IgG responses, but secondary intraperitoneal immunization 13 days later with soluble OA revealed IgE isotype-specific tolerance. The tolerized mice contained splenic suppressor T cells which inhibited IgE but not IgG responses in an adoptive transfer assay. Tolerance was still demonstrable in mice 6 months after the cessation of aerosol exposures. Exposure of low IgE responder rat strains to aerosolized OA tolerized for both IgE and IgG responses.

Adoptive transfer of "persistent' IgE responses in mice in the absence of secondary antigenic stimulation.

Spleen cells were prepared from Balb/c mice immunized 30 days previously with alum-precipitated ovalbumin (OA), which manifested high, persistent titres of anti-OA IgE and IgG. The adoptive transfer of 5.0 X 10(7) such cells to X-irradiated syngeneic recipients produced comparable persistent IgE/IgG responses, in the absence of secondary antigenic challenge. Fractionation procedures indicated that the nylon-wool adherent population from the spleen was the most active in effecting transfer of the response. However, donor T-cells were also required, as pretreatment of the cellular inoculum with anti-Thy 1.2 antiserum ablated transfer. The inclusion of serum containing anti-OA IgG (but not IgE) in the cellular inoculum also blocked the transfer.

Long-lived IgE- and IgG-secreting cells in rodents manifesting persistent antibody responses.

BALB/c mice and BN rats manifesting persistent IgE and IgG responses were examined up to 1 year after immunization. A significant proportion of the ongoing antibody response in these animals survived lethal X-irradiation employing dosages sufficient to deplete B memory cells. The persistent IgE responses in both species were refractory to exogenous isotype-specific suppressor cells taken from tolerant syngeneic animals, which were shown to abrogate primary IgE responses in parallel tests. Employing a novel ELISA-based assay for plaque forming cells, long-lived radioresistant IgE- and IgG-secreting cells were identified in differing ratios in lymph nodes, spleen, and bone marrow of both species. These long-lived cells were shown to arise following maximum antigenic challenge with antigen plus adjuvant, and after repeated low-grade stimulation by antigen alone, including passive inhalation of dilute antigen aerosols.

Isolation of Murray Valley encephalitis virus and other arboviruses in the Ord River Valley 1972-1976.

This paper summarizes the isolation of arboviruses from mosquitoes collected in the Ord Valley between 1972 and 1976. A total of one hundred and ninety five strains of at least fifteen antigenically distinct viruses have been isolated. Seven of these isolates appear to be "new' antigenic types, and several are undergoing further testing. These are three new rhabdoviruses (Kununurra [OR194], a virus provisionally named Kimberley [OR250] and OR189 [provisionally named Parry's Creek]), three ungrouped, non-haemagglutinating viruses (OR379, OR512, OR869) and a virus (OR540) which reacts to Poly Anopheles A world grouping fluid. The remaining viruses have been previously identified in Australia. These include Murray Valley encephalitis (MVE), Kunjin, Kokobera, Sindbis, Koongol, Wongal, Wongorr and a virus in the Corriparta serological group. The most important finding of these studies is that MVE displays as annually recurrent pattern of activity with a peak seasonal transmission rate at the end of the wet monsoon. This is the first definition of a probable endemic focus of MVE activity in Australia. The major vector for the majority of the viruses isolated was, by inference, Culex annulirostris. However, Aedeomyia catasticta was implicated as a major vector of the Corriparta group virus.

Ord River arboviruses--isolations from mosquitoes.

One hundred and thirty presumptive viruses have been isolated from 485 pools made from 23,872 mosquitoes collected in the Ord River area of North-West Australia. One hundred and eleven of the virus isolates isolates came from pools of Culex annulirostis, the dominant mosquito species caught in the vicinity of Kununurra. Forty-five of the viruses pathogenic for newborn mice have been further characterized-19 as Flaviviruses, 1 Alphavirus, 9 Koongol, 1 Mapputta and 15 non-haemagglutinating viruses of which 6 are Corripata. Thirty-seven isolates were from Culex annulirostis, 7 from Aedomyia catasticta and 1 from aedes tremulus. All Corriparta isolates were from Aedomyia catasticta. The Flaviviruses comprised 13 Kunjin and 6 MVE isolates.