Evaluation of immune functions of rainbow trout (Oncorhynchus mykiss)—how can environmental influences be detected?

Abstract

In fish, the first line of defense against infectious microorganisms is based on a broad range of nonspecific humoral and cellular immune mechanisms ('innate immunity') which without prior specific activation can act in forming a more static barrier (Fish Shellfish Immunol. 10 (2000) 243; Dev. Comp. Immunol. 25 (2001) 827). This natural resistance is normally effective enough to protect fish from infectious diseases until specific immune responses are being induced ( Fig. 1; Dev. Comp. Immunol. 25 (2001) 841). Healthy fish exhibit both nonspecific and specific immune responses depending directly on environmental temperature. Pollution of the natural aquatic environment with industrial or agricultural sewage is an important immunosuppressing factor resulting in higher susceptibility to infectious diseases. To date, the possible immunotoxicity of a substance is evaluated using quantification of humoral factors like lysozyme, complement, C-reactive protein or total immunoglobulins but less often using functional assays. Furthermore, most of the functional assays (phagocytosis, respiratory burst, proliferative response) are based on the measurement of the response of resting but not of specific activated immune cells. However, the physiological responses of the immune system to an infection are based on a complex, stepwise activation and proliferation, especially of the specific immune functions after first contact to the microorganisms. In this report we describe in vitro methods for the evaluation of cellular immune functions of different leukocyte populations after specific in vivo triggering of the immune system. Parameters to be evaluated are activation and proliferation of leukocyte populations, phagocytosis and respiratory burst, secretion of antigen-specific antibodies and specific cell-mediated cytotoxicity. Furthermore, challenge models with bacterial (Aeromonas salmonicida) and viral pathogens (Viral Haemorrhagic Septicemia Virus, VHSV) are presented.

Estrogen Signaling through the G Protein–Coupled Estrogen Receptor Regulates Granulocyte Activation in Fish

“…Remarkably, most of the effects of G1 treatment were observed in naive cells and nonvaccinated fish, in sharp contrast with the effects of other estrogens, which are only apparent in a challenge state, in agreement with the postulate by Kö llner et al (69). As estrogens play a prominent role in human autoimmune disorders, our study also suggests that GPER could represent a therapeutic target.…”

An Overview of the Immunological Defenses in Fish Skin

“…To date there have been no conclusive results. First studies focused on fish skin mucosal immunity to evaluate the presence or absence of one or more immune activities; then later works focus on the simultaneous evaluation of several of these immunological parameters to determine their potential roles in host resistance [257][258][259]. At present, works include most relevant immune parameters, or a representative subset, to simultaneously evaluate the quantitative contribution of these immune parameters to host resistance.…”

Desempenho e hematologia de tilápias-do-nilo alimentadas com Saccharomyces cerevisiae e vacinadas contra Streptococcus agalactiae

“…Quando ocorre a invasão de microrganismos, o sistema imune inicia a ativação e a proliferação de leucócitos e trombócitos (Kollner et al, 2002), os quais estão envolvidos na defesa do organismo (Bozzo et al, 2007;Claudiano et al, 2013).…”