Estudio histoquímico e inmunotipificación de poblaciones leucocitarias del timo de alpacas (Vicugna pacos) menores a 60 días de edad

Euthanasia was performed in six alpacas younger than 60 days old, of the Huacaya breed, in the district of Huanta, department of Ayacucho, in Peru. Thymus samples were obtained and embedded in Optimal Cutting Temperature (OCT) medium. Samples were immediately frozen in liquid nitrogen and preserved at -70 oC until ready to be processed. Frozen sample fragments were prepared and covered with organosilane. Immunohistochemistry was done using mouse primary and rabbit secondary antibodies; the reaction was obtained with the use of avidin-biotin-peroxidase complex (ABC), and was regressively stained with Hematoxylin. Specific monoclonal antibodies were utilized to identify Leukocyte Subpopulations in thymus; Five fields of view were evaluated randomly at 400X magnification. The staining distribution and density were classified as negative (-), inconsistent (±), mild (+), moderate (++) and strong ( ). The results indicate that most of the Leukocyte population was found in the thymus cortex and were immature cells with no surface markers; most of the maturing immunomarked cell population were in the medulla of the thymus, and most of them were TCRαβ lymphocytes, and in less proportion TCR γδ lymphocytes, CD8 lymphocytes, B lymphocytes and monocytes/macrophages; and inconsistent values of CD4 lymphocytes. In the thymus cortex, there were low values of TCRαβ lymphocytes and CD8 lymphocytes; inconsistent values of monocytes/macrophages; and no evidence of TCR γδ lymphocytes, CD4 lymphocytes, and B lymphocytes.