- like ▁en zym e ▁similarly ▁acts ▁to ▁activ ate ▁Sp atz le , ▁as ▁loss ▁of ▁S PE ▁does ▁not ▁completely ▁reduce ▁the ▁activity ▁of ▁T oll ▁sign alling . ▁The ▁Im d ▁path way ▁is ▁instead ▁triggered ▁by ▁Gram - negative ▁b acter ia ▁through ▁sol ub le ▁and ▁surface ▁re cept ors ▁( P GR P - LE ▁and ▁L C , ▁respectively ). ▁D . ▁mel an og aster ▁has ▁a ▁fat ▁body , ▁which ▁is ▁analog ous ▁to ▁the ▁human ▁li ver . ▁It ▁is ▁the ▁primary ▁secret ory ▁organ ▁and ▁produces ▁ant im icro b ial ▁pe pt ides . ▁These ▁pe pt ides ▁are ▁secret ed ▁into ▁the ▁hem ol ym ph ▁and ▁bind ▁inf ect ious ▁b acter ia , ▁killing ▁them ▁by ▁forming ▁por es ▁in ▁their ▁cell ▁walls . ▁Other ▁than ▁the ▁fat ▁body , ▁hem ocy tes , ▁the ▁blood ▁cells ▁in ▁D ros oph ila , ▁are ▁analog ous ▁to ▁m amm al ian ▁mon ocy te / mac roph ages , ▁possess ing ▁a ▁significant ▁role ▁in ▁medi ating ▁imm une ▁responses . ▁ ▁It ▁is ▁known ▁from ▁the ▁literature ▁that ▁in ▁response ▁to ▁imm une ▁challenge , ▁hem ocy tes ▁are ▁able ▁to ▁se crete ▁cy tok ines , ▁for ▁example ▁Sp atz le , ▁to ▁activ ate ▁down stream ▁signal ing ▁path ways ▁in ▁the ▁fat ▁body . ▁However , ▁the ▁mechanism ▁still ▁remains ▁unclear . ▁The ▁response ▁to ▁in fection ▁can ▁involve ▁up ▁to ▁ 2 ,