IL-2 enhances standard IFN gamma/LPS activation of macrophage cytotoxicityto human ovarian carcinoma in vitro: A potential for adoptive cellular immunotherapy
X. Han et al., IL-2 enhances standard IFN gamma/LPS activation of macrophage cytotoxicityto human ovarian carcinoma in vitro: A potential for adoptive cellular immunotherapy, GYNECOL ONC, 75(2), 1999, pp. 198-210
Objective. The objective was to evaluate the enhancement of human peritonea
l macrophage cytotoxic in vitro activity by the addition of interleukin-2 (
IL-2) to the standard interferon gama (IFN gamma) and lipopolysaccharide (L
PS) activation procedure used for cellular adoptive immunotherapy in a huma
n ovarian cancer system. This cytotoxic effect of these activated macrophag
es was tested on cells from ovarian cancers of various stages, histology ty
pe, and grade, both prior to chemotherapy and at recurrence, in ovarian car
cinoma cells lines and normal cells. Increased activation of the macrophage
may make it a better candidate for intraperitoneal cellular adoptive immun
otherapy as a component of ovarian cancer therapy. This was not a study of
the mechanism of macrophage killing.
Methods. Ascites specimens were collected from 24 ovarian cancer patients a
t the time of surgery or by paracentesis. The mononuclear cell fraction was
isolated by discontinuous density gradient centrifugation and used as a ce
llular source of peritoneal macrophages (PMs) and primary cultured ovarian
cancer cells. PMs were separated by 1-h adhesion followed by intensive wash
ing to remove floating cells. The floating cells were cultured for 24 h whi
ch left the cancer cells attached after unattached cells were removed by wa
shing. These cells formed a monolayer of cancer cells, which could be subcu
ltured in 22 patients. The cells from the third to fifth passages were used
as target cells without coculture with other cells. PMs were identified by
latex ingestion, and their purity after isolation by adhesion culture was
tested by how cytometry and immunofluorescence. PMs were activated by cultu
ring in the presence of IFN gamma, with or without IL-2, for 18 h followed
by the addition of LPS 6 h prior to use as effector cells in cytotoxicity a
ssays. Ovarian cancer cells of both established cell lines and primary cult
ures were labeled with Cr-51 and utilized as target cells to quantitatively
measure PM-mediated cytotoxicity. Ovarian cancer cells were also coculture
d with PMs for morphologic observations to provide supporting evidence to t
he cytotoxicity assays.
Results. IL-2 enhances the cytotoxicity of the standard IFN gamma/LPS macro
phage activation in this system. Peritoneal macrophages so activated are cy
totoxic to autologous and allogenic primary cultured ovarian tumors and to
ovarian carcinoma cell lines. The macrophages are cytotoxic to cells both p
rior to treatment and at recurrence, but the data from the few recurrent pa
tients did reach statistical significance. This cytotoxicity is not NMC ass
ociated. Normal cells are minimally affected.
Conclusions. IL-2 augmented the standard IFN gamma/LPS method of activating
peritoneal macrophage cell killing of human ovarian cancer cells in this i
n vitro system. The cell killing occurred with autologous and allogenic tum
or cells from patients with primary and possibly recurrent tumors. Activate
d PMs minimally affected the normal cells tested. This enhanced activation
may improve the disappointing results of previous adoptive cellular immunot
herapy human trials and should be considered for ovarian cancer clinical tr
ials. (C) 1999 Academic Press.