Immune Hemolymph Research Articles

Activation of prophenoloxidase and inhibition of melanization in the haemolymph of immune Galleria mellonella larvae

After immunization of Galleria larvae with bacterial lipopolysaccharide, inhibition of haemolymph melanization developed parallel with antibacterial immunity. Failure of melanization was correlated with significantly decreased amounts of active cell-associated phenoloxidase (PO). In normal, nonimmune haemolymph, cellular PO originated from plasma proPO activated by, and largely attached to, the haemocytes; activation was maximal by 150 min. With immune haemolymph, such cellular activation of plasma proPO did not occur. Immune plasma proPO was activated by homogenization, but not by freeze-thawing. Normal plasma proPO was activated by freeze-thawing, but only to a very slight extent by homogenization. Mixing immune plasma with the freeze-thaw activated PO in normal plasma (1:2, v:v) caused a 37%, average reduction in PO activity. The results suggest that inhibition of melanization in immune Galleria haemolymph is caused by plasma factor(s) inhibiting the activation of plasma proPO by haemocytes.

Effect of cobra venom factor on the in vivo immune response in Galleria mellonella to Pseudomonas aeruginosa

Wax moth larvae receiving 0.2 or 0.4 units of cobra venom factor (CVF) per insect, 6 hr after vaccination, have a significantly reduced resistance to Pseudomonas aeruginosa when compared with the normal immune response. Curiously, lower doses of CVF (0.1 units per insect) had a tendency to enhance the resistance of the vaccinated larvae to the pathogen. The CVF had no observable effect on the LD 50 in unvaccinated larvae. The in vitro bactericidal capacity of immune hemolymph, with respect to P. aeruginosa, was lowered significantly by prior incubation of the hemolymph with CVF. The involvement of an invertebrate analog to the vertebrate complement system is discussed.

In vitro growth of bacteria in hemolymph of Galleria mellonella

The in vitro growth patterns of three nonpathogenic species of bacteria in the hemolymph of Galleria mellonella were determined. Similarly, the growth patterns of three pathogenic bacterial species in the hemolymph of normal larvae were compared to patterns in hemolymph from immunized insects. Over the 12-hr observation period, the nonpathogenic species never attained growth in hemolymph that was comparable to that in broth controls. The pathogens in normal hemolymph grew very similarly to controls, whereas, in immune hemolymph the growth of pathogens was greatly inhibited. The growth patterns of both pathogenic and nonpathogenic species of bacteria in normal hemolymph were similar to the in vitro growth patterns previously obtained in whole insect tissue. The possible role of hemolymph in inhibition of growth of bacteria is discussed.