Nicotinamide protects target cells from cell-mediated cytolysis

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Lymphokine-activated killer (LAK) cells induce target cell lysis.
• This process involves DNA fragmentation in target cells.
• The precise molecular mechanisms are not fully understood.

Purpose of the Study:

• To investigate the protective role of nicotinamide against LAK cell-mediated cytotoxicity.
• To elucidate the involvement of poly(ADP-ribose) synthetase in LAK cell lysis.

Main Methods:

• Fibroblast target cells were cultured with LAK cells in the presence or absence of nicotinamide.
• Assays included measuring cell lysis (51Cr release), effector-target cell conjugate formation, and DNA fragmentation.
• Inhibition of poly(ADP-ribose) synthetase was assessed using nicotinamide and 3-aminobenzamide.

Main Results:

• Nicotinamide (5 mM and greater) protected fibroblast cells from LAK cell lysis in a concentration-dependent manner.
• Protection occurred at the target cell level, without affecting conjugate formation or calcium-dependent triggering.
• Nicotinamide prevented DNA fragmentation in target cells.
• 3-Aminobenzamide inhibited lysis, while nicotinic acid did not.

Conclusions:

• Nicotinamide effectively protects target cells from LAK cell-induced lysis.
• The protective effect is linked to the inhibition of poly(ADP-ribose) synthetase.
• Poly(ADP-ribose) synthetase plays a critical role in the DNA fragmentation and lysis pathway mediated by LAK cells.