ASSOCIATION BETWEEN EPIDERMAL INTERLEUKIN-10 SECRETION AND THE ABILITY OF COTRANSPLANTED SKIN FROM NEONATAL DONORS TO PROLONG ADULT ALLOGRAFT SURVIVAL

Cotransplantation of skin from neonatal donors prolongs the survival o f adult skin allografts on rabbit anti-mouse lymphocyte serum-treated and donor bone marrow cell-treated mice relative to controls (the cotr ansplant effect), In B6AF(1) (H2(a/b)) recipients, cotransplants of sk in from C3HeB/FeJ (C3H; H2(k)) neonates up tee 6-7 days old prolonged the survival of adult C3H skin grafts, Skin from 9- to 10-day-old neon ates was inactive, The magnitude of the cotransplant effect declined w ith increasing cotransplant age. Although few class II+ cells are pres ent in skin from < 24-hr-old mice, the numbers of these cells increase rapidly after birth, On days 3-4, when the cotransplant effect is str ong, their numbers in neonatal skin are greater than in adult skin, De velopment of class II expression continues when neonatal skin is graft ed, but with an apparent a-day lag, Because class II+ cell numbers dec line in grafted adult skin, we speculate that this apparent developmen tal lag may be due to Langerhans cells migrating from the graft as the y mature. Epidermal cells from litters of neonates were cultured overn ight and supernatants were tested for interleukin (IL)-10. All 11 samp les from 0- to 4-day-old neonates and 4 of 9 samples from 4- to 7-day- old neonates were positive. IL-10 was found in 1 of 9 samples from don ors 8-16 days old and 1 of 7 samples from individual adult mice, Thus, there is a temporal association between the ability of neonatal skin to produce a cotransplant effect and its ability to secrete IL-10.