The present study reports the results of V-79 Chinese hamster cell sur
vival studies in which Auger electron emission was stimulated in gadol
inium (Gd) after thermal neutron capture, When a porphyrin that had pr
eviously been labeled with boron ((BOPP)-B-10) was also labeled with G
d (Gd-(BOPP)-B-10), the cells were incubated with Gd-(BOPP)-B-10 to as
sess the compound's ability to physiologically transport the Gd into t
he cell, and localize the Gd atoms in or near the cell's critical targ
et, presumably the DNA. It was anticipated that Auger electron emissio
n, stimulated during the Gd-157 (n, gamma) Gd-158 interaction, would i
mpart additional high LET damage to that observed from the alpha-parti
cle and Li ion during the B-10(n, alpha) Li-7 reaction, Following irra
diation with thermal neutrons from the Brookhaven Medical Research Rea
ctor, the effectiveness of the Auger electrons was determined by compa
ring the response of cells incubated with (BOPP)-B-10, where damage wa
s imparted by the boron neutron capture (BNC) products, to that from G
d-(BOPP)-B-10, with equal concentration of B-10 in both solutions, An
Auger effectiveness factor of similar to 2 was found for the Gd-(BOPP)
-B-10 cells, The Auger effectiveness observed with Gd strongly suggest
ed that the (BOPP)-B-10 molecule physiologically transported the Gd3ion intracellularly where it probably bound to DNA, Others have report
ed that Gd3+ does, in fact, complex with DNA, While depositing less en
ergy per interaction than the high LET BNC reaction by-products, Auger
electron ionization was more effective.