EVIDENCE FOR CIRCULATING HEMOCYTE PROLIFERATION IN THE SHRIMP PENAEUS-JAPONICUS

We have observed by flow cytometric analysis that a small but consiste nt percentage of circulating hemocytes in phases S, G2 and M of the ce ll cycle can be detected in Penaeus japonicus. Significantly increased percentages of proliferating hemocytes (similar to three-fold increas e) were observed after stimulation by lipopolysaccharide (LPS), p43 (a n immunosuppressive lymphocyte mitogenic protein produced by Candida a lbicans) and a combination of LPS and p43. Moreover, and similar to si x-fold increase in the percentage of proliferating hemocytes was also observed in animals infected with Fusarium spp., as compared to non-in fected shrimps. Furthermore, [H-3] thymidine uptake in circulating hem ocytes was 26 times greater in LPS stimulated than in non-stimulated s hrimps. The present study suggests that circulating hemocytes of the s hrimp P. japonicus can divide in vivo and that proliferation can be in creased significantly after mitogenic or infectious stimulation. Copyr ight (C) 1996 Elsevier Science Ltd.