Reduced levels of complement C3 after peros administration of ornidazole in normal volunteers

Abstract

SUMMARY
Ornidazole, [a-(chloromethyl)-2-methyl-5-nitroimidazole-
1-ethanol], has recently been succesfully used in the treatment
of active Crohns disease. Although the initial results
were encouraging, the mode of its action is largely unknown.
The present study was undertaken in order to see if ornidazole
has any influence on the immune status, since immunity
plays a significant role in the pathogenesis of inflammatory
bowel disease, especially in Crohns disease. Ten
healthy volunteers received orally 20 mg of ornidazole per
Kg of body weight daily for eight days in two divided doses.
The following immunological parameters were examined
before, two and eight days after the administration of the
drug: serum complement (C3 and C4), serum immunoglobulins
(G, A and M), absolute number of peripheral lymphocytes,
total B-lymphocytes (CD19+), total T lymphocytes
(CD3), T helper-induced CD3+CD4 positive, T
suppressor-cytotoxic (CD3+CD8 positive), Natural Killer
cells (CD3-, CD16+, CD56+), Killer cell (CD8+CD58 positive)
(lymphocyte activation index CD38) and subpopulation
of B lymphocytes (CD20+ and CD5+). Other parameters
examined were serum electrophoresis, number of
platelets and number of white blood cells. The estimation
of lymphocyte subpopulations was achieved by flow-cytometry
technic in total peripheral blood using direct immunofluorence
method with monoclonal antibodies of double
color (double color immunofluorence). Ornidazole significantly reduced the levels of complement 3 after two and
eight days of the peros administration, indicating that exclusive
activation of the alternate pathway of complement
activation occurs. However, other immune parameters
showed no significant changes. It is concluded that ornidazole
affects part of immune consistuents of normal volunteers
if it is administered orally at a dose of 1000 mg per
day for eight days. Further studies are needed in order to
clarify the possible similar effects of the drug on the immune
system of patients with inflammatory bowel disease.
Key Words: Cellular Immunity, Humoral Immunity, Nitroimidazoles,
Ornidazole, Metronidazole, Crohns disease, Inflammatory bowel disease