Quantitative Development of Immunoglobulin (IgG) During Life-Span of Male and Female Laboratory Rat

Abstract

The quantitative development of IgG has been examined in male and female rats at different ages by means of rocket-immuno electrophoresis. In the first half year of the rats life IgG increased in both sexes but with some differences. In female rats the increase in IgG concentration occured earlier than in male rats and reached a higher level. The IgG level was relatively constant from six months to about two years. The males showed higher mean IgG concentrations than female rats. During pregnancy, birth and lactation period the IgG concentration of females was significantly lowered. IgG was again increasing in female rats at weaning.

Young rats at the age of 1–2 days had very low IgG levels. The IgG concentration rose up to the age of about three weeks and then fell abruptly to a lower level. Thereafter it increased again. The sudden decline in IgG concentration of young rats coincided with the increase of IgG in the mother at weaning.

The higher IgG amount in the females at the period of highest reproduction may have some biological significance. Our results demonstrated differences in the IgG level of female and male rats as well as in rats of different age. This fact is especially important for long time experiments and experiments involving rats of different ages and sex.