STRAIN DIFFERENCES IN IMMUNE RESPONSE OF MICE .I. NEONATAL RESPONSE TO SHEEP RED CELLS

Abstract

Neonatal mice of the inbred strains NZB, Balb/c and C57B1 were injected with sheep, pig or chicken red cells at various ages and antibody plaque-forming cell (PFC) responses in their spleens measured. Marked strain differences were found, notably a high early response by NZB mice to sheep cells. Hybrid and backcross experiments suggested that this was genetically controlled by at least 3 genes. C57B1 mice were late in developing a response to all of the antigens tested, The kinetics of the PFC responses were interpreted as favoring an explanation not involving cell division in response to antigen. Thymectomy at birth reduced the PFC responses in 1-month-old mice of all 3 strains to the same low level, while thymectomy after 7 days left the PFC responses intact. The thymus must be present for strain-specific immune responses to develop.