Repeated application of first-layer antiserum improves immunofluorescence staining: a modification of the indirect immunofluorescence staining procedure.

Repeated application of the first-layer antiserum in the indirect immunofluorescence technique considerably improves the immunostaining. The modified method reveals more antigenic sites and increases the contrast between specific and background stainings, particularly where sparsely distributed antigenic areas are to be investigated. The effect of this novel immunostaining procedure is compared with that of the routine procedure and of other modifications. Possible mechanisms for the improving effect are discussed. A procedure of combined modifications is recommended for exploration of non-abundant antigens or for achieving a high-quality photograph.