Abrin lethal dose

Eiklid, K., Olsnes, S., and Pihl, A. (1980) Entry of lethal doses of abrin, ricin, and modeccin into the cytosol of Hela cells. Exp. Cell Res. 126, 321-326. 

Human parenteral toxicity for abrin is approximately 0.1-1 Jig/kg (Romano et al, 2007). However, based on clinical trials on abrin-immunotoxin use for cancer treatment, the human minimum lethal dose by intravenous injection was estimated to be >0.3 Jig/kg without occurrence of serious adverse effects (Gill, 1982). 

Interestingly, the hope for a vaeeination in the treatment against abrin toxieity may be not that far away. In a reeent in vitro and in vivo study, antibodies speeifie to the reeombi-nant abrin A-ehain were shown to reseue eells from toxieity. Importantly, the antibody also proteeted miee from lethal doses of the toxin. The neutralizing effeet of the antibody... 

Abrin is a plant source Type 2 RIP. It is found in Abrus precatorius (rosary pea, Indian licorice, jequirity bean). The toxicology of abrin is considered to be very similar to ricin. A similar Abrus toxin is pulchellin, produced by A. pul-chellus (Millard and LeClaire, 2008). The rosary pea has been reported to be more toxic than castor beans (Griffiths et al, 1994). Species sensitivity is variable and horses are considered to be the most sensitive. The mature goat is considered to be a more resistant species and 2 g of seed/kg body weight is reported as a lethal dose. The lethal dose for cattle is reported at 600 mg of seed/kg body weight. It is likely that abrin is denatured in the rumen (Burrows and Tyrl, 2001). 

The human minimum lethal dose of abrin by intravenous injection is more than 0.3 pg/kg (Gill, 1982) since in clinical trials, patients have tolerated this dose without serious adverse effects. 

Improved survival after a lethal dose of abrin has also been claimed with ascorbic acid pretreatment for 48 h prior to abrin administration (Clark et al., 1981). However, the benefit was completely lost if ascorbate administration occured 15 min or more after abrin exposure, again limiting any clinical application. 

Intraperitoneal injection in mice caused anorexia, drowsiness and diminished then absent reflexes (el-Shabrawy et al., 1987). Guinea-pigs given intraperitoneal abrus seed extract showed similar features (Routh and Lahiri, 1971). The intraperitoneal dose which was lethal to 50% (LD50) of treated mice has variably been reported as 8.34 mg/kg (el-Shabrawy et al., 1987) and 0.02 mg/kg (Lin et al., 1969). This discrepency is likely to reflect differences in purity of the abrin extract and/or experimental conditions. 

Ricin is most toxic when inhaled and is therefore a potential aerosol threat. However, large quantities would he needed to cause toxicity. Ricin is much less lethal when ingested, suggesting poor absorption. The toxicity and lethality of parenteral exposure to ricin are well documented. Abrin which is closely related to ricin in structure is extremely toxic with an LD50 dose for humans of 2 pg/kg. 

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