Immunotherapy with IL-2-stimulated splenocytes reduces in vitro the level of Leishmania donovani infection in peritoneal macrophages.

A study was done in vitro to determine if IL-2-stimulated lymphocytes (LAK cells) would activate infected macrophages to reduce their burden of Leishmania donovani. Macrophage-depleted splenocytes from normal or infected C57BL/6 (H-2b; LshS) mice, stimulated in vitro by the IL-2-containing supernatant of the MLA 144 cell line or by rIL-2, significantly reduced the number of syngeneic resting peritoneal macrophages infected by L. donovani; LAK cells from infected animals were significantly more effective in reducing the numbers of infected cells. Supernatants of MLA 144-stimulated spleen cells and rIL-2-stimulated splenocytes isolated in Millipore chambers also induced a significant reduction of the infection in vitro. Anti-Thy 1.2 eliminated the ability of the supernatant of MLA 144 to induce an activating function in C57BL/6 splenocytes; monoclonal anti-IL-2 abolished the ability of rIL-2 and of the MLA 144 supernatant to stimulate the splenocytes. Infected resting peritoneal macrophages of C57L (H-2b; LshR) mice were more responsive to activation than those of the C57BL/6 animals, irrespective of the phenotype of the stimulating LAK cells. Lymphokine stimulation reverses the immunological anergy induced in T lymphocytes by Leishmania donovani; IL-2-stimulated LAK splenocytes are highly effective in reducing the intensity of experimental visceral leishmaniasis in vitro in peritoneal macrophages.