ed ▁into ▁the ▁o ocy te ▁on ▁its ▁production . ▁ ▁Im m unity ▁▁ ▁Un like ▁m amm als , ▁D ros oph ila ▁f lies ▁only ▁have ▁inn ate ▁imm unity ▁and ▁lack ▁an ▁adapt ive ▁imm une ▁response . ▁The ▁D . ▁mel an og aster ▁imm une ▁system ▁can ▁be ▁divided ▁into ▁two ▁responses : ▁hum oral ▁and ▁cell - medi ated . ▁The ▁former ▁is ▁a ▁system ic ▁response ▁medi ated ▁through ▁the ▁T oll ▁and ▁Im d ▁path ways , ▁which ▁are ▁parallel ▁systems ▁for ▁detect ing ▁micro bes . ▁The ▁T oll ▁path way ▁in ▁D ros oph ila ▁is ▁known ▁as ▁the ▁hom olog ue ▁of ▁T oll - like ▁path ways ▁in ▁m amm als . ▁Sp atz le , ▁a ▁known ▁lig and ▁for ▁the ▁T oll ▁path way ▁in ▁f lies , ▁is ▁produced ▁in ▁response ▁to ▁Gram - pos itive ▁b acter ia , ▁par as ites , ▁and ▁fung al ▁in fection . ▁Upon ▁in fection , ▁pro - Sp atz le ▁will ▁be ▁cle aved ▁by ▁the ▁prote ase ▁S PE ▁( Sp atz le ▁processing ▁en zym e ) ▁to ▁become ▁active ▁Sp atz le , ▁which ▁then ▁bind s ▁to ▁the ▁T oll ▁re ceptor ▁located ▁on ▁the ▁cell ▁surface ▁( F at ▁body , ▁hem ocy tes ) ▁and ▁dim er izes ▁for ▁activation ▁of ▁down stream ▁N F - κ B ▁signal ing ▁path ways . ▁It ▁has ▁been ▁proposed ▁that ▁a ▁second ▁S PE