A SIMPLE METHOD FOR THE IMMUNOCYTOCHEMICAL PROCESSING OF LARGE NUMBERS OF FLOATING SECTIONS AND ITS APPLICATION IN SCREENING FOR MONOCLONAL-ANTIBODIES

A technically simple modification of routine (non-adsorbent) multi-well plates, permitting the simultaneous immunocytochemical processing of hundreds of free-floating sections is described. The adaptations consist of (1) making a 1.5 mm wide perforation in the bottom of each well of the multi-well plate, (2) placing a 6 mm wide 50 mu m mesh nylon filter on the bottom of each well and (3) preincubating the plate with excess inert protein in order to prevent adsorption of protein reagents. During the incubation of the floating sections with the immunocytochemical reagents, the fluid is retained in the well by capillarity, provided the detergent concentrations within the well do not exceed 0.005% (v/v). The wells can be emptied simply and quickly by blotting the plate bottom with a piece of laboratory paper towelling: the fragile sections are gently caught on the filter, without the risk of loss or damage. Sections start floating again as soon as the next reagent is added to the well. The present method drastically reduces the time needed for rinsing and reagent exchange, making immunocytochemistry on free-floating sections feasible as a primary screening method during hybridoma production.