Lymphomyeloid cells, susceptibility to erythrodermatitis of carp and bacterial antigens

Pronounced changes occur in the kidneys carp injected with extracellular product (ECP), lipopolysaccharide (LPS) of A. salmonicida subsp. salmonicida, Freund's complete adjuvant (FCA). ECP caused 50-70% decrease in macrophages and neutrophils, whereas blasts and lymphocyte-like cells increased FCA-elicited increased percentages of blasts and a left shift of neutrophils after LPS injection. After both ECP and FCA injections, the density of major leucocyte types and red blood cells (RBC) in the kidney decreased. LPS generally increased the density of leucocytes. Granulocytes were larger after LPS injection and smaller after FCA injection than control cells. Perhaps ECP eliminates those cells potentially capable of nonspecific defense and FCA stimulates their proliferation. LPS seemed to induce mainly polyclonal lymphocyte-like cell propagation and a reduced replenishment of other leucocytes. Challenge morbidity was 100% of ECP-injected groups, 54.3% of controls, 37.1% of LPS-injected fish and 11.4% of FCA-injected groups. Disease susceptibility may be correlated with availability and functional status of macrophages and neutrophils.