Based on papers :

[1] Klegeris A. McGeer E.G. McGeer PL. Inhibitory action of 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide (PK 11195) on some mononuclear phagocyte functions.Biochemical Pharmacology. 59(10):1305-1314, 2000 May 15.Abstract

[2] Klegeris A. McGeer PL.Interaction of various intracellular signaling mechanisms involved in mononuclear phagocyte toxicity toward neuronal cells.Journal of Leukocyte Biology. 67(1):127-33, 2000 Jan. Abstract

[3] Klegeris A. Walker DG. McGeer PL.Toxicity of human THP-1 monocytic cells towards neuron-like cells is reduced by non-steroidal anti-inflammatory drugs (NSAIDs).Neuropharmacology. 38(7):1017-25, 1999 Jul. Abstract

Methods: Microglia (1.5 x 10 ⁵ cells in 1 ml of solution) were stimulated with 1 micro gm LPS. The cells were incubated for 24 hrs to produce "cytokine juices" in the supernatants . The solution was then used to test neurotoxicity. It was applied to neuroblastoma (SY5Y) cells (1.5 x 10 ⁵ neuron-like cells in 0.5 ml of solution plus 0.5 ml of the cytokine juices.)

The neuroblastoma cells were incubated in the cytokine juice for a period of 24 and 72 hrs and the percentage of cells that died were measured via LDH and MTT assays.

Results:

After 24 hrs: Undetectable death level

After 72 hrs : 20 - 30% of neurons died.

To calculate the approximate connection between IL-6 and/or TNF-alpha neurotoxicity and these results it should be remembered that

Microglia at the level 2 x 10 ⁵ cells in 1 ml of solution , stimulated by 100 ng LPS for a period of 16 hrs secreted (into the supernatants) roughly 10,000 pg/ml of IL-6 , and roughly 1000 pg/ml of TNF-alpha . These figures are according to Lee et al (1993) in the reference:

[4] Lee SC. Liu W. Dickson DW. Brosnan CF. Berman JW. Cytokine production by human fetal microglia and astrocytes. Differential induction by lipopolysaccharide and IL-1 beta. Journal of Immunology. 150(7):2659-67, 1993 Apr 1. Abstract