Serum levels of TNP-specific antibodies after immunization and augmentation of T- and B-cell expansion. (A-C) WT, chimeric, and nonchimeric Rag2^−/−γ_c^−/− mice were immunized with either TNP-KLH or TNP-LPS. Serum levels of antibodies were determined by ELISA in duplicates and the results presented as arbitrary units. Serum levels of TNP-specific antibodies in chimeric and nonchimeric mice immunized with TNP-KLH are represented in A, and those to TNP-LPS are in B. Serum levels of TNP-specific antibodies in WT B6 mice immunized with either TNP-KLH or TNP-LPS are shown in C. Error bars represent SD. (D) Representative flow cytometric data from peripheral blood of a chimeric mouse without vaccination showing low T- and B-cell levels (left panel). In contrast, after vaccination, both T- and B-cells show a huge expansion (right panel). In addition, 2 populations of GFP^dim (36% of GFP-positive) and GFP^high (54% of GFP-positive), marked with circles were identified within the GFP-positive cell population of B220-positive cells. Numbers represent percentages of the proportion of the lymphocytes to the total GFP-expressing cells.