Abstract
The genus Salvator is endemic to South America. In Argentina, the species most abundant widely distributed is Salvator merianae. Particularly in Santa Fe province, the area occupied by populations of these lizards overlaps with areas where agriculture was extended. With the aim of established baseline values for four immunologic biomarkers widely used, 36 tegu lizards were evaluated tacking into account different age classes and both sexes. The results showed there were no differences in total leukocyte counts due to age. Of the leucocytes count, eosinophils levels were higher in neonates compared with juvenile and adults; nevertheless, the heterophils group was the most prevalent leukocyte in the peripheral blood in all age classes. Lymphocytes, monocytes, heterophils, azurophils and basophils levels did not differ with age. There were significant differences in natural antibodies titres, with values being significantly higher in the adults compared with neonate and juvenile lizards. Lastly, complement system activity differenced among the age classes, with the neonates having a low value of maximum hemolysis compared with the juveniles and adults. Statistical analyses within each age group showed that gender was not a factor in the outcomes. Based on the results, we concluded that S. merianae demonstrated age (but not gender) related differences in several immune parameters of the immune system. Having established baseline values for these four widely-used immunologic biomarkers, ongoing studies will seek to optimize the use of the S. merianae model in future research.

Key words: Reptilian, Salvator merianae, immune system, biomarkers, sentinel model.