Nematodes and the spleen: an immunological relationship.

Despite being a major organ of the immune system, the spleen's role in resisting, controlling or simply ameliorating nematode infections has been neglected. A review of both filarial and gastrointestinal nematodes suggests that though it is difficult to fully assess or quantify the organ's importance in vivo, the spleen is prominent in acting against nematode parasites in mammals. One manifestation of this is that transfer of lymphocytes from the spleen of immunised individuals can protect recipients against the disease. Expansion of splenic lymphoid tissue also alludes to its activity during nematode infection. There is a considerable need for investigation of the spleen under natural conditions as well as much more rigorously controlled experiments even in mammals besides birds and other vertebrates.