PHENOTYPIC AND FUNCTIONAL-PROPERTIES OF TH LINES AND CLONES RECOGNIZING LARVAL ANTIGENS OF SCHISTOSOMA-MANSONI

Five T cell clones and two lines were derived from the lymph nodes (LN ) of C57BL/6 mice immunized with radiation-attenuated lung-stage larva e of Schistosoma mansoni. All seven clones/lines were CD4+, CD8- and e xpressed high levels of CD44 and CD45RB surface markers. After prolong ed maintenance in-vitro, with soluble antigen from 18 h schistosomula (SSP), five retained the ability to proliferate readily and release IF Ng in response to concanavalin A (Con-A) and to SSP and/or soluble adu lt worm antigen (SWAP). These Th clones/lines induced significant foot pad DTH reactions when injected with SWAP, but were unable to confer p rotective immunity after transfer to naive recipient mice. This result could be explained by the antigen specificity of the clones/lines, si nce they were not able to release IFNg when cultured in-vitro with liv ing lung-stage larvae. A second possibility is that the high level of CD45RB expression, which is not seen on the surface of pulmonary CD4memory/effector cells isolated directly from protectively-vaccinated m ice, alters the ability of the clones/lines to release IFNg and to ind uce a DTH response in the lungs when they encounter antigen released f rom migrating schistosomula.