Carbohydrate and lectin interactions withEdwardsiella ictaluriand channel catfish,Ictalurus punctatus(Rafinesque), anterior kidney leucocytes and hepatocytes

Abstract

Abstract.Seven isolates ofEdwardsiella ictaluriwere evaluated for channel catfish red blood cell and neutrophil agglutination properties and reactivity with lectins and carbohydrates. All isolates were agglutinated by lectin derived fromRicinus communisand the intensity of the agglutination reaction could be lessened or abrogated by premixing the lectin derived fromRicinus communiswith β‐D‐galactose or α‐L‐fructose.Edwardsiella ictaluriisolates also sedimented much more rapidly when mixed with lectin derived fromRicinus communisthan when mixed with other lectins. PremixingRicinus communiswith β‐D‐galactose had the greatest effect on slowing the rate of sedimentation. Two out of the sevenE. ictaluriisolates were capable of agglutinating channel catfish red blood cells and anterior kidney neutrophils, and this agglutination could be prevented by the addition of β‐D‐mannose. Likewise, the per cent phagocytosis ofE. ictaluriisolate 1389 (the most intense neutrophil agglutinator) could be dramatically reduced by the inclusion of mannose in the assay mixture. Anterior kidney leucocytes and hepatocytes primarily reacted with lectins derived fromCanavalia ensiformis, Ricinus communisandTriticum vulgaris.The presence on channel catfish cells of carbohydrate‐lectin receptors similar in function to those found on mammalian cells and the reaction ofE. ictaluriwith specific lectins suggest that bacterial clearance and lectinophagocyotosis may occur in a similar manner in catfish to that in mammals.