Full text of DOI:10.1086/315890

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Interleukin-12 Regulates the Response to Chemotherapy in Experimental
Visceral Leishmaniasis
Henry W. Murray,1 Christina Montelibano,1
Ron Peterson,2 and Joseph P. Sypek2
1Department of Medicine, Weill Medical College of Cornell
2
University, New York, New York; Genetics Institute,
Andover, Massachusetts
In experimental visceral leishmaniasis, interleukin (IL)–12 initiates control over Leishmania
donovani via Th1 cell activation, interferon (IFN)–g secretion, and granuloma formation.
Because the leishmanicidal effect of conventional therapy, pentavalent antimony (Sb), also
requires T cells and endogenous IFN-g, we tested IL-12 as a determinant of host respon-
siveness to chemotherapy. L. donovani–challenged IL-12p35 gene knockout (KO) mice per-
mitted uncontrolled hepatic infection and failed to respond to Sb. In contrast, 96% of liver
parasites in KO mice were killed by amphotericin B, which acts independently of immune
responses. Exogenous IL-12 combined with Sb was tested in normal mice: low-dose Sb was
converted from weakly to strongly leishmanicidal, and a no-effect Sb dose was converted to
∼100% leishmanistatic. IL-12 plus Sb synergism in normal mice was IFN-g dependent; how-
ever, IL-12 also increased responsiveness to Sb in IFN-g KO mice. Thus, IL-12 regulates host
IFN-g–dependent and –independent responses that permit and/or enhance the leishmanicidal
activity of Sb.
Successful host defense in experimental visceral leishmania-
sis, a disseminated protozoal infection in which resident mac-
rophages of the liver, spleen, and bone marrow are parasitized,
involves a complex Th1 cell–dependent, multicytokine-medi-
ated mechanism (reviewed in [1]). This response, which is prob-
ably initiated by interleukin (IL)–12 and then driven primarily
by interferon (IFN)–g, culminates in macrophage activation,
intracellular killing within tissue granulomas, and long-term
quiescence in residual surviving parasites [1–6]. Prompt and
unimpeded activity of this or a similar mechanism may also
explain why the majority of human infections caused by vis-
ceralizing strains of Leishmania remain subclinical and do not
require therapy [1, 7, 8]. In those patients who do progress to
fully established visceral disease (known as kala-azar), presum-
ably because this protective Th1 cell response failed to develop
or was deactivated [1, 9–13], conventional treatment consists
of pentavalent antimony (Sb) [14, 15]. In India, Sb resistance
has led to the use of amphotericin B (AmB) [14, 15], and, more
recently, miltefosine also has been shown to be active in the
treatment of kala-azar [15, 16].
contrast to AmB and miltefosine [21–23], the efficacy of Sb in
the intact animal with L. donovani visceral infection is deter-
mined by the host cell–mediated immune response [21, 22, 24].
Thus far, studies in athymic (nude) and cytokine gene knockout
(KO) mice have identified T cells and 2 endogenous macro-
phage-activating cytokines, IFN-g and tumor necrosis factor
(TNF), as required factors in the in vivo expression of the
leishmanicidal effect of Sb [22, 24, 25].
However, IFN-g and TNF do not operate alone in control-
ling intracellular L. donovani. Among other cytokines impli-
cated in acquired resistance in this model [1], IL-12 plays a
particularly broad and critical role in both endogenous and
exogenous forms [2–5, 12, 26]. IL-12 mobilizes and supports
the Th1 cell–mediated immune response [27, 28], including that
toward L. donovani [2, 4, 26], and not only acts as the principal
inducer of IFN-g [2–4, 26–28] but also stimulates IFN-g–
independent antileishmanial effects [5]. This breadth of activity
suggested that IL-12 may also regulate the host response to
antileishmanial chemotherapy (e.g., Sb) and prompted this
study in mice that were deficient in IL-12 or were treated with
IL-12.
Sb, AmB, and miltefosine are all directly leishmanicidal to-
ward intracellular Leishmania donovani amastigotes when ap-
plied to macrophages parasitized in vitro [17–20]. However, in
Materials and Methods
Animals.
IL-12p35 KO mice on a BALB/c ϫ 129/Sv back-
Received 5 June 2000; revised 19 July 2000; electronically published 9
October 2000.
Financial support: National Institutes of Health research grant AI 16963.
Reprints or correspondence: Dr. Henry W. Murray, Weill Medical College
of Cornell University, Box 136, 1300 York Ave., New York, NY 10021
(hwmurray@med.cornell.edu).
ground and their wild-type littermates were generated at the Ge-
netics Institute (Andover, MA) [29] and were provided as breeders.
Normal BALB/c mice and IFN-g gene KO (GKO) mice on a
C57BL/6 background were obtained from Jackson Laboratory (Bar
Harbor, ME) [22]. Both male and female KO and wild-type mice
were used; BALB/c mice were females. Mice were 8–15 weeks old
when challenged with L. donovani.
The Journal of Infectious Diseases 2000;182:1497–502
᭧ 2000 by the Infectious Diseases Society of America. All rights reserved.
0022-1899/2000/18205-0027$02.00
Visceral infection. Groups of 3–5 mice were injected via the tail

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Murray et al.
JID 2000;182 (November)
L. donovani challenge and then were treated on day 14 with Sb, as
described above.
IL-12 treatment and anti–IFN-g injections. Murine recombinant
IL-12 (2.7 ϫ 106 U/mg; Genetics Institute) was diluted in saline con-
taining 0.1% bovine serum albumin and administered continuously
at 0.01 or 0.1 mg/d for 7 days via subcutaneously implanted osmotic
pumps (Alzet model 2001; Alza, Palo Alto, CA) [3, 5]. Pumps were
implanted 12 days after L. donovani challenge, and, after 2 additional
days, to allow for some cytokine effect [17], mice then received no
further treatment or received a single injection of Sb on day 14. Liver
parasite burdens were determined 7 days after Sb treatment. In a
preliminary experiment, insertion of pumps containing only saline
plus albumin (no IL-12) did not alter parasite replication or the effect
of Sb (data not shown).
To neutralize IL-12–induced IFN-g, IL-12–treated mice were in-
jected ip with 0.2 mL of rabbit anti–mouse IFN-g antiserum raised
against murine rIFN-g and used in previous studies [3]. Anti–IFN-g
was injected once 2 h before and once 3 days after pump insertion [3].
Injections of 0.2 mL of normal rabbit serum served as a control [3].
Serum IgE. Serum IgE concentrations were generously assayed
by R. Coffman and B. Seymour (DNAX Research Institute of
Molecular and Cellular Biology, Palo Alto, CA) by ELISA [12].
Figure 1. Course of Leishmania donovani infection in livers of con-
trol wild-type mice (⅜) vs. interleukin-12 knockout (IL-12 KO) mice
(ⅷ). Results are from 3 experiments and indicate mean ע SE of the
mean values for 8–12 mice at each time point. Leishman-Donovan
units (LDU) in IL-12 KO mice are significantly higher (P ! .05), com-
pared with that of control mice, at all time points, except at week 2.
Results
Visceral infection in IL-12 KO mice. Before testing chemo-
therapy, we first characterized the response of IL-12p35 KO
mice (BALB/c ϫ 129/Sv background) to L. donovani. Consistent
with the pivotal role of IL-12 in both initiating and supporting
the Th1 antileishmanial response [2, 4, 26–28], KO mice failed
to control visceral parasite replication after week 2, in direct
contrast to infection outcome in wild-type mice (figure 1). Se-
rum IgE levels in KO animals, including those before L. don-
ovani challenge, exceeded those in wild-type mice (table 1),
which suggests an enhanced Th2 cell–type response and effects
induced by IL-4 [12, 26]. Wild-type mice also assembled fully
formed liver granulomas by week 4, at which time 53% ע
6% of infected foci were scored as mature granulomas [1, 22]
(2 experiments, n p 4 mice; figure 2). By week 8, these granu-
lomas were largely devoid of amastigotes or were involuting
(data not shown). In contrast, the tissue reaction at heavily
parasitized foci in IL-12 KO mice did not proceed beyond initial
fusion of infected Kupffer cells, and there was essentially no
mononuclear cell recruitment or granuloma formation at either
vein with 1.5 ϫ 107 hamster spleen–derived L. donovani amastigotes
(1 Sudan strain) [22]. Visceral infection was followed microscopically
by Giemsa-stained liver imprints, in which liver parasite burdens were
measured by counting the number of amastigotes per 500 cell nuclei
times the liver weight in milligrams (Leishman-Donovan units
[LDU]) [22]. The granulomatous response to infection in the liver
was assessed in histologic sections stained with hematoxylin-eosin
and scored as described elsewhere [1, 22].
Antibiotic treatment and treatment with anti–IL-4 monoclonal
antibodies (MAb). Two weeks after infection (day 0), liver par-
asite burdens were determined, and mice then received no treat-
ment, a single intraperitoneal (ip) injection of Sb (sodium stibog-
luconate; Pentostam, Wellcome Foundation, London, UK), or 3
ip injections of AmB sodium deoxycholate [17, 21, 22]. Sb was
given once on day 0 at optimal (500 mg/kg) or suboptimal (10 or
50 mg/kg) doses [17], depending on the intent of the experiment.
AmB (Gensia Laboratories, Irvine, CA) was used at an optimal
dose (5 mg/kg) and was given on days 0, 2, and 4 [21]. Seven days
after treatment was started, all mice were killed, and liver parasite
burdens were measured. The percentage of parasite killing was
determined as follows [22]: [(day 0 LDU Ϫ day 7 LDU in treated
mice)/day 0 LDU] ϫ 100. The percentage of inhibition of parasite
replication was determined as follows: {[(day 7 LDU in untreated
mice Ϫ day 0 LDU) Ϫ (day 7 LDU in treated mice Ϫ day 0 LDU)]/
(day 7 LDU in untreated mice Ϫ day 0 LDU)} ϫ 100. Differences
were analyzed by use of a 2-tailed Student’s t test.
Table 1. Serum IgE levels in mice infected with Leishmania donovani.
Serum IgE levels, mg/mL (n)
Weeks after infection
Wild-type control
IL-12 KO
0 (uninfected)
2.7 ע 0.3 (5)
3.9 ע 0.4 (4)
15.2 ע 7.1 (4)
17.7 ע 3.3 (8)
10.9 ע 4.1 (5)
11.2 ע 5.1 (4)
31.4 ע 12.2 (4)
40.9 ע 9.3 (7)a
2
4
8
In some experiments, IL-12 KO mice were also treated with 3
ip injections of 1 mg of normal rat IgG or rat anti–murine IL-4
MAb (11.B.11; provided by C. Reynolds, Biologic Response Mod-
ifiers Program, National Cancer Institute, Frederick, MD) [12].
Mice were injected with IgG or MAb on days 1, 7, and 14 after
NOTE. Data are mean ע SE from 2 experiments. Serum was obtained from
control and interleukin-12 knockout (IL-12 KO) mice before (week 0) and 2, 4,
and 8 weeks after challenge with L. donovani.
a
P ! .05 vs. wild-type control.

JID 2000;182 (November)
IL-12 Regulates Response in Leishmaniasis
1499
Figure 2. Photomicrographs showing liver histologic reaction to Leishmania donovani infection. A, Control wild-type mice 4 weeks after infection
show mature granuloma formation with recruited mononuclear cells surrounding and infiltrating core of fused parasitized Kupffer cells. By week
8 (not shown), granulomas in wild-type mice were present at 195% of infected foci and were either devoid of amastigotes or starting to involute.
B, Interleukin-12 knockout (IL-12 KO) mice 8 weeks after infection show heavily parasitized foci that have provoked either no cellular response
(large arrow) or Kupffer cell fusion alone with little mononuclear cell influx (small arrow). At week 4, granuloma formation in IL-12 KO mice
(not shown) was also essentially absent at infected foci. Original magnification, ϫ315.
week 4 or week 8 (2 experiments, n p 6 mice; figure 2). These
results, including those in figures 1 and 2, mirror those recently
reported in C57BL/6 IL-12 KO mice also infected with L. dono-
vani [26].
burdens at week 2 (610 ע 67 LDU) versus KO mice injected
with normal IgG (1008 ע 72 LDU; 2 experiments, n p 6 mice
per group). However, in the same 2 experiments, anti–IL-
4–treated mice did not show an enhanced response to Sb (500
mg/kg) given on day 14 (data not shown), which suggests that
the suppressive actions of IL-4 were not responsible for im-
paired responses to Sb in IL-12 KO mice.
Effect of exogenous IL-12 on the response to Sb. The finding
that endogenous IL-12 was required for Sb responsiveness sug-
gested that exogenous IL-12 might also enhance the effect of
Sb. IL-12 induces both IFN-g–dependent and –independent
antileishmanial action in L. donovani–infected mice [3–5]; there-
fore, we tested combination therapy in both IFN-g–intact nor-
mal BALB/c mice and in GKO animals.
Endogenous IL-12 regulates the response to chemotherapy.
The effect of chemotherapy was tested in mice infected 2 weeks
earlier, at which time the mice had well-established liver parasite
burdens. Wild-type control animals responded to both Sb and
AmB with high-level leishmanicidal activity, as judged by
87%–89% reductions in parasite burdens between days 0 and 7
(table 2). AmB-induced killing was also seen in IL-12 KO animals
(96% reduction in liver burden on day 7). However, the same
KO mice showed a clear-cut defect in the response to Sb and
failed to express any leishmanicidal activity after optimal-dose
treatment (500 mg/kg). In addition, inspection of day 0
(1026 ע 161 LDU) and day 7 LDUs in Sb-treated KO animals
(2129 ע 199 LDU; table 2) indicated that liver parasite burdens
had doubled, despite treatment. Compared with untreated KO
mice, these Sb-treated KO animals showed only 14% inhibition
of parasite replication on day 7. Thus, in the absence of endog-
enous IL-12, Sb also induced little in vivo leishmanistatic effect.
Effect of anti–IL-4 on the response to Sb. Serum IgE levels
in L. donovani–infected IL-12 KO mice were increased (table
1), which suggests that the failure to respond to Sb might also
reflect suppressive effects of an IL-4–driven, Th2 cell–associated
mechanism [12]. Increased IL-4 release has also been reported
in in vitro–restimulated spleen cells from L. donovani–infected
IL-12 KO mice [26]. Therefore, IL-12 KO mice were injected
3 times with anti–IL-4 or normal rat IgG during the 2 weeks
before Sb treatment (see Materials and Methods).
Table 2. Effect of antileishmanial chemotherapy in wild-type (WT)
and interleukin-12 knockout (IL-12 KO) mice.
Liver parasite burden, LDU
Treatment
Day 0
Day 7
Killing, %
WT control mice
None
Sb
AmB
IL-12 KO
None
Sb
759 ע 121
924 ע 147
99 ע 25a
81 ע 37a
0
87
89
—
—
1026 ע 161
2316 ע 249
2129 ע 199b
37 ע 21a
0
0
96
—
—
AmB
NOTE. Data are mean ע SE for 8–12 mice at each time point, from 2–3
experiments. Two weeks after challenge with Leishmania donovani (day 0), mice
received no treatment, a single injection of 500 mg/kg of Sb, or 3 alternate-day
injections of 5 mg/kg of AmB. AmB, amphotericin B; LDU, Leishman-Donovan
units; Sb, antimony.
a
P ! .05 vs. day 0 value.
Sb effect represents 14% inhibition of parasite replication (see calculations
b
Anti–IL-4 treatment by itself allowed KO mice to express
some resistance to L. donovani, as judged by lower liver parasite
in Materials and Methods).

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Murray et al.
JID 2000;182 (November)
Table 3.
Effect of immunochemotherapy by use of interleukin
genous IL-12. Although the latter role was clear-cut for conven-
tional treatment (Sb), the efficacy of AmB was fully maintained
in the absence of IL-12 and the Th1 cell mechanism that IL-12
initiates [27, 28]. This finding underscores the previously recog-
nized capacity of AmB to act entirely independently of T cells,
macrophage-activating cytokines (IFN-g and TNF), and the in-
flammatory mononuclear cell tissue response (granuloma for-
mation) [21, 22, 25]—the principal host components that together
control this intracellular infection [1]. In contrast, the leishman-
icidal effect of Sb and, in large measure, its secondary leishman-
istatic action appear to require each of the preceding endogenous
immunologic cofactors, as well as IL-12, all probably acting in
a coordinated fashion as expressions of the Th1 cell response [1].
The minimal response of IL-12 KO mice to Sb (14% inhibition
of parasite replication), akin to Sb’s absent effect in T
cell–deficient nude mice [24], differed from the response in GKO
mice tested in parallel (data reported elsewhere [22]). Although
GKO mice also failed to express any killing effects after treatment
with 500 mg/kg of Sb, these animals did respond with complete
inhibition (100%) of parasite replication during the treatment
period [22]. The latter finding, together with the barely detectable
effect of Sb in IL-12 KO mice demonstrated here (0% killing and
14% inhibition; table 2) suggested that endogenous IL-12 may
regulate in vivo responsiveness to chemotherapy via 2 pathways
in Sb-treated animals: one probably via induction of IFN-g,
which acts with Sb to induce parasite killing [3, 4, 22], and the
other via an IL-12–responsive, IFN-g–independent mechanism
[5], which appears to act with Sb to permit a more limited effect,
inhibition of parasite replication. The latter pathway would be
present in IFN-g KO mice, enabling them to respond to Sb with
leishmanistatic activity; neither pathway would be available to
IL-12 KO animals.
(IL)–12 plus antimony (Sb) in normal mice.
Liver parasite burden,
LDU
Killing, Inhibition,a
Treatment, dose
Day 0
Day 7
%
%
None (control)
IL-12, 0.01 mg/d
Sb, 50 mg/kg
IL-12 ϩ Sb, 50 mg/kg
IL-12 ϩ Sb, 50 mg/kg,
ϩ anti–IFN-g
IL-12 ϩ Sb, 50 mg/kg,
ϩ normal serum
Sb, 10 mg/kg
1341 ע 102 2537 ע 149
0
0
10
63
0
19
—
—
—
—
—
2314 ע 254
1212 ע 90
491 ע 58b
—
1151 ע 125
14
—
—
—
—
582 ע 67b
2348 ע 198
1401 ע 119c
57
0
0
—
16
95
IL-12 ϩ Sb, 10 mg/kg
NOTE. Data are mean ע SE for 6–7 mice per group, from 2 experiments.
Twelve days after infection, pumps delivering continuous IL-12 in the indicated
doses were implanted in normal BALB/c mice. Two days later (day 0), mice
received no additional treatment or single injections of the indicated doses of Sb,
and liver parasite burdens (expressed in LDU) were determined 7 days later (day
7). Anti–IFN-g or normal rabbit serum was administered 2 h before and 3 days
after IL-12 pumps were inserted. IFN-g, interferon-g; LDU, Leishman-Donovan
units.
a
Percentage of inhibition (see Materials and Methods) was determined for
groups in which neither IL-12 nor Sb induced a killing effect.
b
P ! .05 vs. day 0 value.
P ! .05 vs. day 7 value in untreated mice.
c
Because normal mice infected 2 weeks before testing respond
with high-level leishmanicidal activity to optimal doses of IL-
12 (1 mg/d) or Sb (500 mg/kg) when used alone [3, 17], we tested
suboptimal doses of both agents in combination, including es-
sentially no-effect doses of Sb. Under these conditions (table
3), coadministration of IL-12 at 0.01 mg/d clearly enhanced the
efficacy of Sb and converted 50 mg/kg of Sb from weakly to
strongly leishmanicidal and 10 mg/kg from no effect to leish-
manistatic. Injecting anti–IFN-g antiserum largely inhibited the
leishmanicidal efficacy of combination therapy (table 3), which
suggests that endogenous IFN-g induced by IL-12 was pri-
marily responsible for the synergistic effect.
Nevertheless, in separate experiments in which GKO mice
were treated (table 4), an IL-12–inducible, IFN-g–independent
response also appeared to be involved in the mechanism of
combination therapy. GKO mice respond to optimal-dose IL-
12 (1 mg/d) with L. donovani killing [5]; therefore, 10-fold less
IL-12 (0.1 mg/d) was used in combination with optimal-dose
Sb (500 mg/kg), to which GKO mice show no leishmanicidal
response [22]. The results in table 4 indicate that IL-12 plus Sb
also induces synergistic killing effects in the absence of endo-
genous IFN-g.
Injections of anti–IL-4 did not enhance the efficacy of Sb in
IL-12 KO mice. Thus, we concluded that the inability of these
animals to respond to Sb was probably related to the failure
to develop a Th1 cell response (including deficient IFN-g se-
cretion [4, 26]) rather than to additional inhibitory effects of
an unopposed Th2 cell mechanism. In Leishmania major–
infected BALB/c mice, which express a particularly prominent
IL-4–induced Th2 cell mechanism, responsiveness to Sb is also
Table 4. Effect of interleukin (IL)–12 plus antimony (Sb) treatment
in interferon (IFN)–g gene knockout (KO) mice.
Liver parasite burden, LDU
Treatment, dose
Day 0
Day 7
Killing, %
None (control)
IL-12, 0.1 mg/d
Sb, 500 mg/kg
IL-12 ϩ Sb
2524 ע 201
3764 ע 289
2196 ע 179
2712 ע 198
1204 ע 99a
0
13
0
—
—
—
Discussion
52
In addition to reemphasizing the pivotal role of IL-12 in re-
sistance to visceral L. donovani and that tissue granuloma as-
sembly does not proceed in its absence [4, 26], these results extend
the analysis of host regulation of responsiveness to anti-
leishmanial chemotherapy by defining a required role for endo-
NOTE. Data are mean ע SE for 6 mice per group, from 2 experiments.
Experiments were carried out in gene KO mice, as described in table 3, except
that higher doses of both IL-12 and Sb were used. LDU, Leishman-Donovan
units.
a
P ! .05 vs. day 0 value.

JID 2000;182 (November)
IL-12 Regulates Response in Leishmaniasis
1501
11. Ghalib H, Piuvezam M, Skeily Y, et al. Interleukin-10 production correlates
with pathology in human Leishmania donovani infection. J Clin Invest
1993;92:324–9.
12. Murray H, Hariprashad J, Coffman RL. Behavior of visceral Leishmania
donovani in an experimentally-induced Th2 cell–associated response
model. J Exp Med 1997;185:867–74.
intact during the time the drug is administered [30]. Excessive
endogenous IL-4 does influence outcome in this setting, how-
ever, because it promotes progression of L. major infection once
Sb therapy is discontinued [30].
The results derived from the use of IL-12 as a treatment serve
to complement the identification of the role of endogenous IL-
12 by indicating that synergy with Sb can also be induced by
the cytokine in exogenous form. Treatment with locally injected
(intralesional) IL-12 plus systemic Sb has also been used suc-
cessfully in L. major–infected footpads [31], and systemic ad-
ministration of IL-12 plus conventional antibiotics has also
proven active in models of other diverse infections [32–34]. The
capacity of exogenous IL-12 to act with Sb against L. donovani
in both normal and IFN-g–deficient mice indicates the breadth
of IL-12’s action, making it attractive as the cytokine com-
ponent of future immunochemotherapeutic antimicrobial reg-
imens. As judged by the prior use of IFN-g [15, 35–37], such
combination regimens may have a role in the treatment of vis-
ceral leishmaniasis and might also prove useful in other allied
intracellular infections.
13. Ghalib HW, Whittle JA, Kubin M, et al. IL-12 enhances Th1-type responses
in human Leishmania donovani infections. J Immunol 1995;154:4623–9.
14. Berman JD. Human leishmaniasis: clinical, diagnostic, and chemotherapeutic
developments in the last 10 years. Clin Infect Dis 1997;24:684–703.
15. Murray HW. Treatment of visceral leishmaniasis (kala-azar): a decade of
progress and future approaches. Int J Infect Dis 2000 (in press).
16. Herwaldt BL. Miltefosine: the long-awaited therapy for visceral leishmani-
asis? N Engl J Med 1999;341:1840–2.
17. Murray HW, Berman JD, Wright SD. Immunochemotherapy for intracellular
Leishmania donovani infection: interferon-g plus pentavalent antimony. J
Infect Dis 1998;157:973–8.
18. Croft SL, Davidson RN, Thorton EA. Liposomal amphotericin B in the treat-
ment of visceral leishmaniasis. J Antimicrob Chemother 1991;28(Suppl B):
111–8.
19. Neal RA, Croft SL. 1984: an in vitro system for determining activity of
compounds against the intracellular form of Leishmania donovani. J An-
timicrob Chemother 1984;14:463–75.
20. Croft SL, Snowdon D, Yardley V. The activities of four anticancer alkyll-
sophospholipids against Leishmania donovani, Trypanosoma cruzi, and
Trypanosoma brucei. J Antimicrob Chemother 1996;38:1041–7.
21. Murray HW, Hariprashad J, Fichtl R. 1993. Treatment of experimental vis-
ceral leishmaniasis in a T cell–deficient host: response to amphotericin B
and pentamidine. Antimicrob Agents Chemother 1993;37:1504–5.
22. Murray HW, Delph-Etienne S. Role of endogenous gamma interferon and
macrophage microbicidal mechanisms in host response to chemotherapy
in experimental visceral leishmaniasis. Infect Immun 2000;68:288–93.
23. Murray HW, Delph-Etienne S. Visceral leishmanicidal activity of hexadecyl-
phosphocholine (miltefosine) in mice deficient in T cells and activated mac-
rophage microbicidal mechanisms. J Infect Dis 2000;181:795–9.
24. Murray HW, Oca MJ, Granger AM, Schreibe RD. Requirement for T cells
and effect of lymphokines in successful chemotherapy for an intracellular
infection: experimental visceral leishmaniasis. J Clin Invest 1989;83:1253–7.
25. Murray HW, Jungbluth A, Ritter E, Montelibano C, Marino MW. Visceral
leishmaniasis in mice devoid of tumor necrosis factor and response to
treatment. Infect Immun 2000 (in press).
Acknowledgments
We are grateful to Robert Coffman and Brain Seymour (DNAX
Corporation) for performing the IgE assays.
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