Cellular hemolymph response of Simulium vittatum (Diptera:Simuliidae) to intrathoracic injection of Onchocerca lienalis (Filarioidea:Onchocercidae) microfilariae.
Hemolymph cellular changes in Simulium vittatum Zetterstedt in response to intrathoracic injection with Onchocerca lienalis Stiles were characterized by increased numbers of tissue fragments that contained cells embedded within a noncellular matrix. Cell numbers within the matrix fragments increased both for sham and microfilariae-injected files, indicating a blastogenic response to injection alone. Morphological characteristics of fixed, Giemsa-stained cells within these tissue fragments were most similar to those previously described for prohemocytes. The total population of freely circulating hemocytes collected 24 h after injection also responded to injection alone. Differential cell counts showed a complex pattern of changes that was influenced strongly by increased numbers of prohemocytes at 24 h in microfilariae-injected flies. Fat body fragments collected in hemocoel perfusates at 24 h were fewer when flies were maintained at 27 degrees C than at 21 degrees C. More fat body fragments were collected from microfilariae-injected flies than from control and sham-injected flies held at 27 degrees C. Injection of 1.25-5 micrograms of lipopolysaccharide per fly did not elicit similar hemolymph-associated matrix tissue and fat body changes, indicating that S. vittatum response to microfilaria infection and bacteria infection are likely to involve different mechanisms.
Cupp
M S
MS
Department of Veterinary Science, University of Arizona Tucson 85721, USA.
Chen
Y
Y
Cupp
E W
EW
D000818:Animals; D002452:Cell Count; D005216:Fat Body / Q000166:cytology / Q000276:immunology; D006434:Hemocytes / Q000166:cytology; D006458:Hemolymph / Q000276:immunology*; D007111:Immunity, Cellular; D008070:Lipopolysaccharides / Q000276:immunology; D009854:Onchocerca / Q000276:immunology*; D012843:Simuliidae / Q000276:immunology*
D008070:Lipopolysaccharides