Sera from patients suffering from the autoimmune skin diseases pemphigus vulgaris and bullous pemphigoid were used to demonstrate the presence of intercellular substance (ICS) or bullous pemphigoid antigen (BPA) on the surface of the schistosomula of Schistosoma mansoni which had penetrated mouse and human cadaver skin, and mouse skin percutaneously. Both ICS and BPA were absent from mechanically transformed schistosomula or those formed in the peritoneal cavity of mice. Schistosomula which penetrated slowly through mouse or human skin in vitro, acquired more ICS or BPA than those which penetrated rapidly.
During percutaneous infections of mice, schistosomula recovered from skin after 2h and 24h had acquired large quantities of these materials whereas those which were recovered from skin after 10min had no detectable ICS or BPA. These materials must be shed during subsequent migration since schistosomula from lungs and liver, and 7-week old adults do not possess them.
Histological examination of both mouse and human skin revealed that the schistosomula remained in the epidermis for varying lengths of time. Schistosomula which remained there for more than 2h became vacuolated, whereas schistosomula which were present in the dermis at 2h appeared undamaged.
On cercarial penetration of human skin, the granular layer of the epidermis became disrupted or condensed. The implications of these findings are discussed.