Neonatal foreskin substrate has limitations for the immunofluorescent screening of monoclonal antibodies.

Two monoclonal antibodies to type IV collagen showed a marked decrease in the labeling of the dermal-epidermal junction of neonatal foreskin while the basement membrane around dermal blood vessels was brightly stained. In contrast, these antibodies labeled the junction and dermal blood vessels with approximately equal intensity when adult skin of nonforeskin site was used as substrate. Other antibodies to matrix molecules (bullous pemphigoid antigen, epidermolysis bullosa acquisita antigen, and laminin) showed excellent staining of both the dermal-epidermal junction and dermal blood vessels in both neonatal foreskin and adult skin. Further, the ultrastructural appearance of the substrates appeared identical. The implication is that neonatal foreskin is not a good substrate to use for the routine screening of monoclonal antibodies to matrix components by indirect immunofluorescence since a "false negative" evaluation may occur.