[Inhibition of expression of HLA-A- and B-antigens in the presence of Percoll].
In monocytes isolated by means of percoll a partial or complete suppression of specific cytotoxic reactivity of HLA-A and B-antigens could be observed when corresponding HLA sera were used. This phenomenon is also evident in monocytes gained by means of adherence and then resuspended in percoll. The same is true in lymphocytes resuspended in percoll and even occasionally if a mixture of complement with percoll is used in the cytotoxic test or if percoll is being added in the course of the second phase of the test. After washing the blood elements thrice with barbital buffer and resuspension in the same buffer, blood cells will reveal a normal expressivity of HLA-A and B-antigens. From the investigations carried out percoll may be concluded to inhibit HLA-A and B-antigens. The extent of percoll influence will depend on the concentration of percoll solutions and the titre of HLA serum. A hypothesis which might explain the inhibitory influence of percoll is discussed.