“…Our results show that heterograft reaction of the cornea is quite well suppressed by an adequate systemic dose of 6-MP. This finding is in good agree-ment with previous experimental and clinical studies on homograft reaction (Cleasby & al., 1964(Cleasby & al., , 1966Alberth, 1965, Polack, 1965, 1966Lanzieri & al., 1966;Leibowitz & Elliott, 1966). Histopathologic study, however, confirmed the presence of slight or moderate infiltration of chiefly mononuclear inflammatory cells around the grafts; further, toxic signs of varying degree were observed in the blood cell count.…”