Journal of Lipid Research, Vol 25, 1090-1095, Copyright © 1984 by Lipid Research, Inc.
Inhibition of phytohemagglutinin-induced lymphocyte mitogenesis by lipoxygenase metabolites of arachidonic acid: structure-activity relationships
CE Low, MB Pupillo, RW Bryant and JM Bailey
Phytohemagglutinin (PHA)-induced mitogenesis of mixed mouse spleen
lymphocyte populations, measured by [3H]thymidine incorporation, was
completely inhibited by micromolar concentrations of certain
hydroxyeicosatetraenoic acids (HETE's). These are lipoxygenase metabolites
of arachidonic acid which are synthesized in considerable concentrations by
macrophages, lymphocytes, and other components of the immune system when
appropriately stimulated. In the studies described here, the structural
requirements for the maximum antimitogenic activities were examined. A
series of monohydroxylated HETE's were prepared using a singlet oxygen
photochemical procedure or by enzymatic synthesis from arachidonic acid
substrate, and isolated by HPLC. Isomers containing different numbers of
double bonds were synthesized using the appropriate unsaturated fatty acid
as substrate, and the functional importance of the OH and carboxylic
functions was tested using various acetoxy- and carbomethoxy derivatives. A
serum-free mitogenesis assay system was used for testing, which minimized
binding of the fatty acids by serum proteins and increased the inhibitory
potency of the various HETE's several-fold. It was found that inhibition of
cell proliferation was related to: hydroxyl proximity to the center of the
eicosatetraenoic acid, decreasing in the order: 9 greater than 11 greater
than 12 greater than 15 greater than 8 much greater than 5; the number of
double bonds in the fatty acid chain, decreasing in the order: 15-OH, 20:4
greater than 15-OH 20:3 much greater than 15-OH, 20:2 much greater than
15-OH, 20:0; and the 15- position functional group as well as the
1-carboxylic group, decreasing in the order: 15-hydroxy, 1-carboxylic
greater than 15-acetoxy, 1- carboxylic much greater than 15-hydroxy,
1-carbomethoxy greater than 15- acetoxy, 1-carbomethoxy.(ABSTRACT TRUNCATED
AT 250 WORDS)