Ontogeny of T-cell mitogen response in Lewis rats: I. Culture conditions and developmental patterns

Spleen and thymus cells from female Lewis rats 2 to 220 days old were cultured with phytohemagglutinin (PHA) or Concanavalin A (Con A). The optimal dose of Con A for mitogenesis ranged from 1 microgram/ml for suckling rats to 125 micrograms/ml for adult rats. Thymus cells differed from spleen cells in that they required 72 hours for maximum thymidine incorporation; whereas spleen cells attained maximum incorporation within 48 hours. Thymidine uptake in unstimulated spleen cell cultures was high in the neonate and decreased with age. Maximum splenic cell responses to Con A increased from very low levels in the 2-day old to adult levels by 3 weeks coincident with weaning. Maximum PHA responses of splenocytes matured more slowly, reaching adult levels by 8 weeks. Thymus cell responses to Con A and PHA were mature from birth.