Vaccine Induced Immunity to Schistosoma mansoni: Spleen Cell ProliferativeResponses Before and After Challenge in Balb/C Mice Given Irradiated or Normal Schistosomula

摘要

Spleen cell proliferative responses in BALB/c mice were assessed at varyingintervals after vaccination or primary Infection and subsequent cercarial challenge. Mice were vaccinated with 500 50-Krad-irradiated S. mansoni schistosomula somula or infected with 20 normal schistonomula. Prior to challenge, splenic responses in the two test groups to phytohemagglutinin (PHA) declined progressively while schistosomula (SMA)-driven responses increased. After challenge, PHA responses increased in both groups on day 3 then declined to significantly lower levels compared to normal controls. On day 3 after challenge, SMA responses in vaccinated mice were vigorous, and greater than twice the responses in infected mice. Thereafter, responses in vaccinated mice declined while responses in infected mice increased on days 7 through 25 but dropped markedly by day 39. For the infected group, in vitro depletion of plastic adherent cells or Lyt+2.2 lymphocytes resulted in augmented SMA responses 3 days post-challenge by 400% and 100%, respectively.