Immunoelectronmicroscopical demonstration of in vivo bound complement C3 in psoriatic lesions

The presence of in vivo bound complement (C3) within the stratum corneum of 4 psoriatic cases is demonstrated ultrastructurally by the use of the peroxidase-antiperoxidase multistep technique. The positive reaction product was located in the intercellular space and on the surface of the parakeratotic cells within the horny layer. The membranes of the horny cells were not altered and peroxidase granules could also not be detected within their cytoplasm. The explanation of this finding as well as its pathogenetic significance is discussed.