Ultrastructural Evidences for Endothelial Cell - Leukocytes Interactions: Margination and Migration Evidencias Ultraestructurales de las Interacciones Células Endoteliales - Leucocitos: Marginación y Migración

Resumen

SUMMARY: Leukocyte-endothelial cell interactions have a pivotal role in immune responses. In our study Ten adult wistaralbino rats weighing 180-200 g were used to obtain tissue samples. The animals were sacrificed by decapitation under ether anes thesia.The lymph nodes of the animals were then quickly removed. Specimens were immersed in the zinc iodide-osmium tetroxide (ZIO)solutation by Niebauer et al. (1969) and kept in the dark for 2 hours in this solution from temperature for fixation/staining. Samples wereprocessed according to routine plastic embedding tecnique. Semithin sections of 1µm thick were cut and stained with methilene blue-azure II for light microscopic examination. We used zinc iodide-osmium tetroxide staining tecnique to distinguish endothelial c ell fromleukocytes.Present data supports the understanding of this unique relationship as documented by figures. KEY WORDS: Leukocytes; Margination; Migration. INTRODUCTION Leukocyte adhesion to vascular endothelium is aninitial and rate-limiting step in the cascade of events thatlead to inflamation. Two important determinants of theleukocyte-endothelial cell adhesion observed duringinflamation are shear forces generated by the movement ofblood within the microcirculation and adhesionglycoproteins expressed on the surface of leukocytes andendothelial cell (Granger & Kubes, 1994; Farr & De Bruyn,1975). Recirculation of leukocytes predominantlylymphocytes is essential for the function of immune sytem.The selectivity of the leuokocyte infiltration of tissue thatoccurs in some types of inflamation could be exerted bythe stimulus for margination on the stimulus for a migrationit is noted that selective margination of lymphocytes occursin post-capillary venules of lymphoid tissues. Recently itis well documented that this complex process is mediatedby certain adhesion molecules including selectins,intercellular adhesion molecules,integrins and their ligands(Shimizu