Passive transfer of acquired resistance to Schistosoma mansoni in laboratory mice.

Serum taken from mice 12-15 weeks after a primary infection of Schistosoma mansoni transfers to normal recipients a partial resistance to subsequent schistosome challenge. The transfer of immunity is evident not only in the reduced recovery of mature parasites from the liver, but also in the diminished numbers of invading schistosomula recovered of resistance equivalent on average to 47% of that found in actively immunized animals, the results suggest that humoral factors play a major role in the effector mechanism of schistosome immunity.