Vol 27 No 2 December - The Indian Society for Parasitology

Journal of Parasitic Diseases
Vol. 27 (2) Dec. 2003, pp. 85-93
Induction of colony-stimulating factors by Leishmania
donovani amastigote soluble antigens
PRIYA SINGAL AND PRATI PAL SINGH*
National Institute of Pharmaceutical Education and Research, S.A.S. Nagar-160 062, India
Leishmania donovani amastigote antigens soluble in culture medium (LDAA; 0.01-10 mg/kg), following
intravenous injection in BALB/c mice, induced the production of serum colony-stimulating factors (CSFs);
1 mg/kg LDAA induced maximum response (137 ± 18 colonies). In vitro, LDAA (0.01-1 mg/ml) induced
mouse macrophages (MØs) to elaborate CSFs in the conditioned medium (CM); 0.1 mg/ml LDAA induced
maximum production by peritoneal (73 ± 9 colonies), splenic (69 ± 10 colonies) and bone marrow-derived
MØs (77 ± 10 colonies). Both in vivo and in vitro, the CSF production could be observed as early as 6 h,
reached maximum by 24 h and then levelled-off to background levels by 72 h. Pre-treatment of LDAA with
rabbit anti-LDAA polyclonal antibody significantly (p60%). The colony forming unit-GM counts in the spleen and femur of
LDAA-treated mice showed a maximum increase of 2.7- and 2.4-fold, respectively. These data, apparently
for the first time, suggest that L. donovani amastigote soluble antigens can induce the production of CSFs.
Key Words : Amastigotes, Colony-stimulating factors, Leishmania donovani, Macrophages, Soluble
antigens.
INTRODUCTION
eishmania sp. are dimorphic protozoan parasites
Lthat cause a wide range of human diseases called
leishmaniases, which include self-healing cutaneous
lesions, localized or diffuse mucosal lesions and fatal
visceral infections. In the mammalian hosts, the
amastigote stages of Leishmania parasite are
obligatorily intracellular as they reside and multiply in
the phagolysosomal compartments of macrophages
(MØs) and dendritic cells (Bogdan and Rollinghoff,
1998). Leishmania donovani, the causative agent of
human visceral leishmaniasis (VL), causes VL in
BALB/c mice also (Cotterell et al., 2000a).
The colony-stimulating factors (CSFs; mol. wt. 18-90
* Corresponding Author
kDa) are a group of glycoprotein hormones, which
regulate the differentiation and proliferation
programme of the committed progenitor cells by
binding to their specific surface receptors, in vitro
(Metcalf, 1989; Metcalf, 1991); in vivo they stimulate
hematopoiesis (Donahue et al., 1986). The lineage
specific CSFs i. e. granulocyte (G)-CSF (G-CSF) and
MØ (M)-CSF (M-CSF), stimulate G and M colony
formation, respectively. GM-CSF, on the other hand,
supports the formation of colonies consisting mainly
of G, M and eosinophils, whereas multi-CSF
(interleukin-3; IL-3) induces colonies containing cells
of different lineages. The genes for mouse and human
CSFs have been cloned, and large quantities of
recombinant CSFs can now be produced (Metcalf,
1991). Structurally, M-CSF is a homodimer, whereas
G, GM- and multi-CSFs consist of a single polypeptide
chain. The CSFs are active at picomolar