QUANTIFICATION OF THE POPULATION AND PHAGOCYTARY ACTIVITY OF HEMOCYTES OF RESISTANT AND SUSCEPTIBLE STRAINS OF Biomphalaria glabrata AND Biomphalaria tenagophila INFECTED WITH Schistosoma mansoni

Abstract

Among the determinant factors in the resistance and susceptibility of Biomphalaria to Schistosoma mansoni, hemocytes play an important role. Aiming at studying S. mansoni/Biomphalaria interactions related to hemocytes, the first step is certainly connected with the standardization of this cell population in uninfected Biomphalaria. In this way, quantification of this cell population in hemolymph, as well as its phagocitary capacity, have been determined for the first time. Furthermore, using susceptible and resistant strains of B. glabrata and B. tenagophila, the hemocytegram and phagocytary capacity of hemocytes after infection with S. mansoni were determined too. Resistant and susceptible strains of B. glabrata (BA and BH, respectively), as well as resistant and susceptible strains of B. tenagophila (TAIM and CF, respectively) were infected with 10 miracidia of the LE and SJ strains of S. mansoni, respectively. These infected snails and respective uninfected controls were assessed in relation to the number of circulating hemocytes and alteration in the phagocytary capacity, by using Zymozan and MTT. Reading was taken by means of a spectrophotometer at 5 hours and 1, 2, 5, 10, 20 and 30 days after infection. The results showed a decrease in population of the circulating phagocytary cells, 5 hours after infection. One day post-infection, the circulating cells of the susceptible snails showed an increased metabolic activity, but the same event could not be observed in the resistant strains. In the subsequent observation periods, significant differences among the strains studied could not be observed until the end of the experiment.

Differences in the number of hemocytes in the snail host Biomphalaria tenagophila, resistant and susceptible to Schistosoma mansoni infection

“…This decrease in the number of hemocytes detected in the first hours after exposure to S. mansoni has been described as a characteristic feature of B. tenagophila (Seta et al, 1996;Bezerra et al, 1997). Cochennec-Laureau et al, in 2003, when analyzing mollusks of the species Ostrea edulis, both infected and non-infected by Bonamia ostraea, observed that the number of hemocytes infiltrating tissues was higher in infected individuals than in noninfected ones and that this number increased with the intensity of the infection.…”

A contribution to the pathobiology of Biomphalaria glabrata hemocytes

“…Cell count was performed in a mixture of 10 µl hemolymph with a 5% neutral red solution, and examined in Neubauer chamber. Redstained cells were identified as granulocytes and the nonstained ones as hyalinocytes (Bezerra et al 1997).…”

“…After 3h incubation in a water bath at 37°C, it was added 5 mg/ml PBS, pH 7.2, of MTT (3-4,5 dimetil tetrazolium bromide, Sigma, US), and the water bath continued for more 2 h, at 37°C. After that, 1 ml of isopropanol-HCl 0,04 N was added, homogenized, centrifuged and the supernatant analyzed with a Hitachi U-2000 spectophotomer, under 570 nm wave-length (Bezerra et al 1997). …”

Hemócitos de Bradybaena similaris e Megalobulimus abbreviatus (Gastropoda, Stylommatophora)

“…A maioria dos estudos com hemócitos de gastrópodes referem-se a espécies dos gêneros Biomphalaria (Preston, 1910) e Lymnaea Lamarck, 1799 sob condições, ou não, de infecção (Müller, 1956;SMinia, 1972;harriS, 1975;yoShino, 1976;cheng & guida, 1980;loverde et al, 1982;Jeong et al, 1983;JoKy et al, 1983;SMinia et al, 1983;Barraco et al, 1993;BeZerra et al, 1997BeZerra et al, , 2003Matricon-gondran & letocart, 1999;ruSSo & lagadic, 2004;BarBoSa et al, 2006;SantoS & diniZ, 2009;SantoS et al, 2011;cavalcanti et al, 2012). O conhecimento sobre o sistema imunológico dos gastrópodes é importante, principalmente o conhecimento dos hemócitos de caracóis não infectados, para que em futuros estudos, seja possível avaliar a ação do parasitismo sobre o sistema de defesa do hospedeiro.…”