Presence of Ca2+ is obligatory for the cytotoxic activity of dengue virus-induced cytotoxic factor.
The present study was undertaken to investigate the role of calcium ions (Ca2+) in the cytotoxic activity of the cytotoxic factor (CF) produced by T lymphocytes of the dengue type 2 virus (DV)-infected mouse spleen. It was observed that CF prepared in Ca2(+)-free medium had no cytotoxic activity on normal mouse spleen cells suspended in Ca2(+)-free medium but had activity on cells suspended in medium having Ca2+. The cytotoxic activity of CF was restored by substitution with calcium chloride, the optimal dose being 10(-7) M. CF induced influx of Ca2+ as measured by uptake of radiolabelled calcium chloride (45Ca), in the susceptible target cells, macrophages (M phi) and T lymphocytes, but had no effect on CF-resistant B lymphocytes. Calcium channel blocking drugs, like verapamil, nifedipine and diltiazem, inhibited the cytotoxic activity of CF and also the CF-induced influx of 45Ca in M phi and T cells. Thus, presence of Ca2+ is obligatory for the cytotoxic activity of CF and the cell death is associated with increased intracellular Ca2+.
Khanna
M
M
Postgraduate Department of Microbiology, K.G. Medical College, Lucknow, India.
Chaturvedi
U C
UC
Dhawan
R
R
Tekwani
B L
BL
Pandey
V C
VC
D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002470:Cell Survival; D003602:Cytotoxicity, Immunologic; D003715:Dengue / Q000276:immunology*; D003716:Dengue Virus / Q000502:physiology*; D055646:Killer Factors, Yeast; D008264:Macrophages / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D011506:Proteins / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology
D002121:Calcium Channel Blockers; D055646:Killer Factors, Yeast; D011506:Proteins; D002118:Calcium