Comparative mitogenic responses of T-cells and B-cells in spleens of mice of varying age.

Mouse spleen cell mitogenic responses to Phytohemagglutinin (PHA), conconavalin A (con A), staphylococcal enterotoxin B (SEB) and lipopolysaccharide (LPS) were studied as a function of age. In CD-1 mice, spleen cell DNA synthesis in response to stimulation by PHA, con A and SEB varied from 18% - 33% of adult values for the first 3 weeks of life. By 6 weeks, the PHA response was 63% of the adult response and achieved adult values by 8 weeks of life. In contrast to these T-cell responses, DNA spleen cell synthesis in response to LPS was approximately that of adults as early as 7 days after birth. When spleen cell mitogenic responses were studied in C57B1/6J mice a similar pattern emerged. C57 spleen cell responses to PHA, con A and SEB varied from 24% - 54% of adult values for the first 3 weeks of life. By 4 weeks, spleen cell responses to PHA and con A were approximately those of adults. Again, C57 spleen cell responses to LPS were equivalent to adult values as early as 7 days after birth.