1. Several studies have been conducted to analyze the effect of temperature on macrophage activation in Rainbow Trout (Oncorhynchus mykiss).  

Effects of temperature on Macrophage Activating Factor (MAF):

Head kidney cell suspensions are generally used to analyze MAF activity.  MAF activity if considered present if respiratory burst activity increases significantly.  Different temperatures are used, e.g. 6C, 10C and 18C, to compare MAF activity (Hardie, 1994).  Head kidney macrophages and leukocytes are isolated at different temperatures and incubated 0-48 hours prior to MAF stimulation (Hardie, 1994). After a pre-incubation at the appropriate temperature MAF is added to cells. After 48 hours of incubation, respiratory burst activity of the macrophages is measured and compared to the leukocyte respiratory burst activity (Hardie, 1994).  

Figure 1 (Hardie, 1994)

       Results have shown that MAF production in Rainbow Trout leukocytes is temperature dependent in vivo and in vitro.  MAF production at 14C has been shown to synthesize and release MAF immediately, even at 6C.  However, if cells are pre-incubated for 48 hours MAF production is significantly reduced.  Since MAF production in trout is T-cell dependent, at low temperatures (6C) T-cells show a non-adaptability characteristic.  This non-adaptability will likely cause a lack of growth factors for leukocyte immune responses.  It has been well established that fish T-cell responses are sensitive especially at low temperatures.

Figure(Hardie, 1994)

Figure 3 (Hardie, 1994)

Figure 4 (Hardie, 1994)

Figure 5 (Hardie, 1994)

                                                                               Macrophage Activation