Mr. Vestey et Rl. Lochmiller, SPONTANEOUS LYTIC ACTIVITY AGAINST HETEROLOGOUS ERYTHROCYTES IN COTTON RAT (SIGMODON HISPIDUS) SERUM, Comparative biochemistry and physiology. Part A, Physiology, 109(1), 1994, pp. 133-138
Although innate immunity has been well studied in laboratory animal mo
dels, no such documentation exists for wild species possessing a diver
sity of physiological adaptations to their environment. We examined th
e blood sera of 188 hispid cotton rats (Sigmodon hispidus) for natural
ly occurring hemolytic activity against heterologous erythrocytes. Nin
ety two percent of the blood sera samples from cotton rats lysed sheep
erythrocytes. All sera tested against chicken erythrocytes showed hem
olytic activity, while only 44% of the same sera could lyse bovine ery
throcytes. No hemolytic activity was present in cotton rat sera agains
t erythrocytes from other rodent species (Eastern woodrat, Neotoma flo
ridana, and pine vole, Microtus pinetorum). Hemolytic activity was hea
t labile and appeared to be mediated through the classical complement
pathway. The protective nature of this hemolytic factor is unclear but
it is probably directed at a more relevant molecule. These data, alon
g with other reports of naturally occurring target specific serum fact
ors in the cotton rat, may reflect the importance of innate protective
mechanisms to small mammal populations.