Técnica alternativa para fechamento de placas de microtécnica em exames de histocompatibilidade HLA

Abstract

The HLA system consists in a group of cell membrane proteins: the HLA-A, B, C, DR, DQ and DP molecules. Arnong the main uses of this system we can find the farnily and random studies for bone marrow trans plantation, as well as the cross-matches before kidney transpiantations. An irnportant rnethodological advance in the study of the HLA system arised very soon, with the development of a rnicrolyrnphocytotoxiciiy technique, used until nowadays, in which the mononuclear blood cells bearing the HLA molecules are used as target for cytotoxicity reactions developed in specialized rnicrotrays. The final step of the serological rnethod consists to cover the tray with a glass cover slip and to read the reactions at an inverted light microscope. We present an alternative technique to dose the tray, which perrníts the utilization of a common light microscope. In this proposed method, a gel (Kaiser's rnodífied gelatin) is placed gently over the tray at the end of the usual technique, following eosin staining and formaline fixation. After that, the tray is placed, in inverted position, at a common light microscope and read in the same way as the usual rnethod. Twenty preliminary tests were perforrned unti/ now, with a very good reprodutibilily in terrns of reaction patterns; no mor phological altera tions were seen in these tests, when cornpared with the conventional technique. The use of this gelatin proved to be econornical, easy to perforrn and very reproducible. The trays covered with the gelatin were read again each two weeks for six rnonths, and we did not find any difference in the reaction patterns as well as in the cell morphology.