Immunologic reactions carried out at a liquid-solid interface

Active slides coated with an antigen layer of bovine serum albumin can specifically adsorb a layer of antibodies nearly twice as thick (70 to 80 Å) as that adsorbed on inactive slides (40 Å). Active slides are prepared by evaporating in vacuo a nickel layer ? 4000 A thick, in the presence of a magnetic field oriented perpendicularly to the slide, the surface being metallized facing the south pole of the field. The activity of a slide varies with an exact period of 24 hours. Fully active at night, a slide gradually loses its activity from sunrise on but has regained it at sunset. When the assays are carried out 2 flights below ground, no inactivation takes place. Two floors of thick concrete prevented the inactivating radiation from reaching the slides. Heavy shielding by lead or a thin sheet of μ metal also prevent inactivation from occurring.