High hepatic natural killer cell activity in murine lupus.

This study demonstrates a profound elevation of NK activity, as measured by cytotoxicity to YAC-1 targets in a 4-h incubation 51Cr-release assay, of freshly isolated hepatic NPC from both MRL/lpr and (NZB X NZW)F1 mice. This marked increase was not observed in splenic or peripheral blood NK. The hepatic NK were nonadherent, radioresistant, Ly-1-,2-, and AGM1+. Furthermore, biologic response modifiers can further augment hepatic NK activity in these autoimmune strains.

Temporal stability of insular avian malarial parasite communities.

Avian malaria is caused by a diverse community of genetically differentiated parasites of the genera Plasmodium and Haemoproteus. Rapid seasonal and annual antigenic allele turnover resulting from selection by host immune systems, as observed in some parasite populations infecting humans, may extend analogously to dynamic species compositions within communities of avian malarial parasites. To address this issue, we examined the stability of avian malarial parasite lineages across multiple time-scales within two insular host communities. Parasite communities in Puerto Rico and St Lucia included 20 and 14 genetically distinct parasite lineages, respectively. Lineage composition of the parasite community in Puerto Rico did not vary seasonally or over a 1 year interval. However, over intervals approaching a decade, the avian communities of both islands experienced an apparent loss or gain of one malarial parasite lineage, indicating the potential for relatively frequent lineage turnover. Patterns of temporal variation of parasite lineages in this study suggest periodic colonization and extinction events driven by a combination of host-specific immune responses, competition between lineages and drift. However, the occasional and ecologically dynamic lineage turnover exhibited by insular avian parasite communities is not as rapid as antigenic allele turnover within populations of human malaria.

IFN-gamma is not an essential mediator of murine antibody responses in vitro.

We have used purified murine gamma-interferon (Mu IFN-gamma) and anti-Mu IFN-gamma monoclonal antibody to study the participation of gamma-interferon (IFN-gamma) in in vitro plaque-forming cell (PFC) responses to antigen. We have studied several supernatants with T-cell replacing factor (TRF) activity as well as helper T-cell dependent anti-sheep red blood cells (SRBC) PFC responses. Our findings demonstrate that neither TRF- nor T-cell mediated responses are critically dependent upon IFN-gamma.

Patterns of Knemidokoptes jamaicensis (Acari: Knemidokoptidae) infestations among eight new avian hosts in the Dominican Republic.

The ectoparasitic mite Knemidokoptes jamaicensis Turk burrows into the cornified epithelium of the legs and feet of Passeriform birds and has been reported from 12 species of North American birds. Here we establish new host and distribution records for K. jamaicensis from eight species of birds from three habitats in the Dominican Republic. These species include Hispaniolan pewee (Contopus hispaniolensis Bryant), northern mockingbird (Mimus polyglottos L.), Cape May warbler (Dendoica tigrina Gmelin), prairie warbler (Dendroica discolor Vieillot), palm warbler (Dendroica palmarum Gmelin), green-tailed warbler (Microligea palustris Cory), black-crowned palm tanager (Phaenicophilus palmarum L.), and Greater Antillean bullfinch (Loxigilla violacea L.). Rates of infestation were as great as 18.2% but varied between species and habitats. Mites were far more common in the dry desert thorn scrub than they were in higher elevation and more moist habitats, despite the fact that many of the affected species had distributions that spanned multiple habitat types. Results suggest that the abundance of scaley-leg mites is controlled by the abundance of suitable host species and by specific ecological conditions that promote transmission.

Primary central nervous system T-cell lymphoma in aids patients: case report and literature review.

According to the published data, most primary central nervous system lymphomas (PCNSLs) are B-cell lymphomas; primary T-cell lymphomas are rare. In a search of the MEDLINE database, we found only 6 cases of primary T-cell PCNSL. Here, we present the case of a 43-year-old man with AIDS, not on highly active antiretroviral therapy, who presented with focal neurologic symptoms and was found on magnetic resonance imaging to have multiple brain lesions. A biopsy showed T-cell lymphoma, and the patient was subsequently treated with whole-brain radiation, to marked clinical response. Reported cases from the literature of primary T-cell PCNSL in AIDS patients are summarized in this review.

The role of autoreactive T-cell lines in the restoration of the immune response to sheep red blood cells in C57Bl/6-lpr/lpr mice.

Although autoimmune-prone mice bearing the lymphoproliferation (lpr) gene have polyclonally activated B cells and high serum titers of autoantibodies, they mount poor immune responses to exogenous antigens. In addition, they exhibit very low or nonexistent autologous mixed lymphocyte responses. Previous studies have shown that autoreactive T-cell clones have immunoregulatory properties: they can help suppress, or contrasuppress an immune response. Here we show that two autoreactive T-cell lines, GB4 and B1H1, can restore the defective response of C57Bl/6-lpr/lpr mice to the antigen sheep red blood cells. This restoration is antigen-dependent and requires the presence of other T cells.

The syngeneic T-T lymphocyte reaction (STTLR). I. Induction of primary T anti-T cell proliferative responses in T cell cultures stimulated with self- and antigen-reactive T cells.

The generally accepted "Gershonian" view of immunoregulation attributes T cell-mediated regulation of immune responses to the activities of discrete T cell subsets with specialized functions such as help, suppression, and contrasuppression. Several observations made in our laboratory are not compatible with this paradigm. For instance, careful quantitations of carrier-specific T cell help to hapten-specific B cells in an adoptive transfer system yielded complex dose-response curves that could not be explained on the basis of interactions between discrete subsets of helper and suppressor cells. Rather, the results were most easily interpreted according to a model based on the following assumptions: (1) Regulation of helper T cell activity is a dose-dependent, dynamic property of T cell populations that exhibit a high degree of connectivity (self-recognition) and (2) helper T cells have the ability to perform different functions, depending on the current activity of other interacting lymphocytes. A good example of cloned T cells capable of performing multiple immunoregulatory functions was provided by the IEk-specific self-reactive Lbd line which provided help, suppression, and contrasuppression to T cell dependent PFC responses (see Quintáns et al., 1986). Since these effects were strictly dependent on the levels of antigen-specific T cell help, we hypothesized that Lbd cells interacted with other T cells to modulate their function. In this paper, we directly test the hypothesis that activated T cells can interact directly with resting T cells and describe the proliferative component of a syngeneic T cell anti-T cell response induced by antigen and self-reactive helper and cytotoxic T cells. In a follow-up report, we will describe the effector component of the T anti-T cell response.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of murine hepatic accessory cells and splenic dendritic cells.

Accessory cells are required for proliferation and antibody synthesis of B lymphocytes and proliferation of T lymphocytes in primary immune responses in vitro. The obligatory cells derived from the spleen are referred to as dendritic cells. Accessory cells were isolated from normal adult livers which were functionally interchangeable with splenic DC. Both hepatic accessory cells (AC) and splenic DC adhere firmly to plastic culture dishes or wells within 2 hr; but hepatic AC, unlike splenic DC, do not detach during 22 hr additional incubation. Hepatic AC, unlike splenic DC, are not lysed or inactivated by monoclonal antibody 33D1 and C'. Hepatic AC and splenic DC are similarly sensitive to irradiation in vivo and insensitive to irradiation in vitro. Hepatic AC are separated with cells which are predominantly phagocytic and FcR+ and contain nonspecific esterase. Both hepatic AC and splenic DC are suppressed or eliminated by activation of NK cells in vivo, a phenomenon prevented by prior elimination of NK cells.

[Effect of interoceptive stimulation of the stomach on photically evoked potentials of the visual cortex with reference to blood pressure and heart rate in the cat]. / Der Einfluss interozeptiver Reizungen des Magens auf photisch evozierte Potentiale des visuellen Kortex unter Berücksichtigung des Blutdrucks und der Herzfrequenz bei der Katze.

In ten chloralose narcotized, relaxed and constantly oxygenated cats the stomachs were dilated with two different pressures in acute experiments. Photically evoked potentials (PEP) were derived from the visual cortex of the animals. The aim of the work was to find out in which respect the processing of an exteroreceptive stimulus (light stimulus of only 200 ms) in the visual analyzer can be influenced by an interoceptive stimulation. Besides, it had to be established to which extent the visceral stimulation leads to a change of other vegetative parameters. Qualitative alterations of different PEP-parameters, blood pressure and heart rate of the experimental animals were examined at different stomach pressures. Changes of the positive and negative amplitudes and the time of the negative component of the primary complex of the evoked potential have been observed. Moreover, there could be registered an increase in blood pressure depending on the height of stomach pressure. The heart rate was not influenced. Further studies will have to clarify whether the changes of the PEP are produced by the interoreceptive stimulus or by the changes of blood pressure or respiration.

Phosphorylation of endothelial nitric oxide synthase in response to fluid shear stress.

Endothelial cells release nitric oxide (NO) more potently in response to increased shear stress than to agonists which elevate intracellular free calcium concentration ([Ca2+]i). To determine mechanistic differences in the regulation of endothelial constitutive NO synthase (ecNOS), we measured NO production by bovine aortic endothelial cells exposed to shear stress in a laminar flow chamber or treated with Ca2+ ionophores in static culture. The kinetics of cumulative NO production varied strikingly: shear stress (25 dyne/cm2) stimulated a biphasic increase over control that was 13-fold at 60 minutes, whereas raising [Ca2+]i caused a monophasic 6-fold increase. We hypothesized that activation of a protein kinase cascade mediates the early phase of flow-dependent NO production. Immunoprecipitation of ecNOS showed a 210% increase in phosphorylation 1 minute after flow initiation, whereas there was no significant increase after Ca2+ ionophore treatment. Although ecNOS was not tyrosine-phosphorylated, the early phase of flow-dependent NO production was blocked by genistein, an inhibitor of tyrosine kinases. To determine the Ca2+ requirement for flow-dependent NO production, we measured [Ca2+]i with a novel flow-step protocol. [Ca2+]i increased with the onset of shear stress, but not after a step increase. However, the step increase in shear stress was associated with a potent biphasic increase in NO production rate and ecNOS phosphorylation. These studies demonstrate that shear stress can increase NO production in the absence of increased [Ca2+]i, and they suggest that phosphorylation of ecNOS may importantly modulate its activity during the imposition of increased shear stress.