Teleost Immunity Research Articles

Temperature-mediated processes in teleost immunity: the effects of temperature on membrane immunoglobulin capping on channel catfish b lymphocytes

1. 1. In order to better understand ligand-induced redistribution of membrane receptors and lymphocyte activation in ectothermie vertebrates, flow cytometry was used to monitor the effects of both in vivo acclimation temperature and in vitro assay temperatures on the kinetics of monoclonal antibody-induced membrane immunoglobulin (mIg) capping on channel catfish lymphocytes. 2. 2. It was observed that the kinetics of mIg capping were dependent on in vitro assay temperatures, in vivo acclimation temperatures, and the length of time of in vivo acclimation. In the latter situation in vivo acclimation offish to 27, 22 and 17°C was considered complete after 3 weeks, while acclimation to 12°C required a minimum of 5 weeks. 3. 3. The energies of activation required for mig capping ranged from 33 to 24kcal/mol; lower energies of activation were observed with lower temperature acclimation. 4. 4. It was also noted that the lower energies of activation were associated with concomitant decreases in cellular phospholipid saturated/unsaturated fatty acid ratios. 5. 5. It appears that channel catfish B cell mig capping, presumably a requisite for immune function, can be significantly affected by environmental temperatures; most likely such effects are attributable to changes in plasma membrane viscosities.

Temperature-mediated processes in teleost immunity: differential effects of temperature on catfish in vitro antibody responses to thymus-dependent and thymus-independent antigens.

An in vitro culture system was employed to ascertain the effects of different temperatures on the anti-hapten antibody-secreting cell responses of channel catfish leucocytes to murine thymus-dependent (TD) and thymus-independent (TI) antigens. The magnitudes of primary responses to a TI antigen (TNP-LPS) and secondary responses to a TD antigen (DNP-KLH) were relatively independent of in vitro culture temperature. The kinetics of each of these responses as a function of temperature was characterized by a Q10 of 2. In contrast, the magnitudes of primary responses to TD antigens (DNP-KLH and DNP-HoSA) were suppressed at lower in vitro temperatures. Furthermore, it was observed that some of the low temperature suppression of primary responses to TD antigens could be abrogated by appropriate low temperature in vivo acclimation. These findings are interpreted as supporting the hypothesis that low environmental temperatures immunosuppress fish by virtue of differential inhibitory effects on the generation of carrier-specific helper cells.

Temperature-mediated processes in teleost immunity: Differential effects of [formula omitted][formula omitted] and [formula omitted][formula omitted] temperatures on mitogenic responses of channel catfish lymphocytes

The in vitro mitogenic responses of channel catfish peripheral blood leucocytes to ConA and LPS were differentially affected by both in vitro and in vivo temperatures. The magnitude of the response to LPS was relatively independent of both in vitro culture temperature and in vivo acclimation temperature. The magnitude of the response to ConA was suppressed at lower in vitro temperatures although this suppression could be reduced by lower in vivo acclimation temperatures. In vitro temperature-shift experiments indicated that channel catfish PBL could respond to ConA at a lower in vitro temperature if first stimulated with ConA at a higher in vitro temperature. The converse, however was not true in that channel catfish PBL did not respond at a higher in vitro temperature after an initial stimulation with ConA at a lower in vitro temperature. This latter failure to respond could not be attributed to the induction of a suppressor cell (or factor) by exposure to ConA at a lower temperature. These studies, when coupled with other available data on channel catfish PBL subpopulations, are interpreted as supporting the hypothesis that low temperature immunosuppression in fish may result from preferential inhibitory effects on T cells rather than B cells.

Temperature-mediated processes in teleost immunity: homeoviscous adaptation in teleost lymphocytes.

AbstractIn vitro studies with pinfish (Lagodon rhomboides) lymphocytes demonstrated that the temperature to which a fish is acclimated in vivo affects the temperature dependence of lymphocyte responses to mitogenic stimulation with conconavalin A (ConA) in vitro, i.e., at an in vitro temperature of 20°, the lymphocytes of 17° acclimated fish responded to ConA better than the lymphocytes of 27° acclimated fish. Fluidity measurements of plasma membranes from lymphocytes isolated from both cold- and warm-acclimated pinfish were made using fluorescence polarization spectrophotometry and the fluorescent membrane probe, 1,6-diphenyl-1,3,5-hexatriene. While the membranes of cold-acclimated pinfish were more fluid than those of warm-acclimated fish when both were measured at the same temperature, the fluidities were equal when measured at the respective acclimation temperatures. These results support the hypothesis that the process of homeoviscous adaptation of lymphocyte plasma membranes may be an important aspe...

Amyloidosis in Still's disease.

The roles of IL-4 and IL-4Rα in Th2-mediated immunity have been well characterized in humans and other mammals. In contrast, few reports have been documented in ancient vertebrates. Several putative IL-4– and IL-4Rα–like molecules were identified recently from a few fish species, providing preliminary insight into the occurrence of Th2-type immunity in teleosts. However, functional determination still is required to address this hypothesis. To this end, these two molecules were characterized functionally in zebrafish (<i>Danio rerio</i>). Besides the identification of a full-length IL-4Rα molecule and an isoform lacking most of the cytoplasmic region as predicted previously, two novel alternatively spliced soluble variants with the extracellular domain only also were identified. Zebrafish IL-4Rα (<i>Dr</i>IL-4Rα) shared overall conserved structural features of the IL-4Rα family. Immunofluorescence staining showed that <i>Dr</i>IL-4Rα distributed on B cells. In vitro binding assays demonstrated that zebrafish IL-4 (<i>Dr</i>IL-4) can bind specifically to <i>Dr</i>IL-4Rα. In vivo administration of <i>Dr</i>IL-4 significantly upregulated B cell proliferation and Ab production. These <i>Dr</i>IL-4–elicited immune responses were downregulated by the administration of zebrafish soluble IL-4Rα or by <i>Dr</i>IL-4Rα blockade using anti–<i>Dr</i>IL-4Rα Abs. In addition, Th2-related cytokines or transcription factors were upregulated by <i>Dr</i>IL-4. The <i>Dr</i>IL-4–<i>Dr</i>IL-4Rα interaction promoted CD40 expression on B cells and enhanced the CD154–CD40 costimulatory response, both of which are crucial for the initiation of Th2-type immunity. To our knowledge, this is the first report showing that a possible Th2-mediated regulatory mechanism may have appeared before the divergence of teleosts and mammals. These results add greater insight into the evolutionary history of adaptive immunity.