Specificity of alloreactive T lymphocytes that adhere to lung stage schistosomula of Schistosoma mansoni

Schistosomula of Schistosoma mansoni acquire murine major histocompatibility complex (MHC)³ antigens during the early stages of their development in mice (1). Products of the K, I, and D regions have been detected on the surface of the parasites by immunofluorescence (1). Furthermore, cell populations containing alloreactive and TNP-specific murine cytolytic T lymphocytes (CTL) have been shown to adhere specifically to schistosomula bearing the appropriate MHC antigens (2,3). The adherence of the lymphocytes to the schistosomulum surface does not result in morphologically detectable damage to the worm (2). In experiments that demonstrate the adherence of alloreactive lymphocytes to schistosomula, populations of spleen cells previously stimulated in vivo or in vitro were incubated with parasites recovered from allogeneic and syngeneic mice (2). The adherent cells were capable of lysing allogeneic tumor target cells and bore the Thy-1 antigen as determined by immunofluorescence (2). It was proposed that the cells were CTL (2) and that their adherence to schistosomula might serve as a useful model of the early events involved in the interaction of these effectors with their targets (2,3). In this paper, we present additional evidence concerning the Ly-phenotype and antigenic specificity of the alloreactive T lymphocytes that adhere to schistosomula. Our results provide further support for the concept that this cell population consists primarily of CTL.