T cell subset distribution and B cell hyperreactivity in mice expressing interleukin‐4 under the control of major histocompatibility complex class I regulatory sequences

Abstract

Abstract Transgenic mice in which interleukin‐4 (IL‐4) is expressed under the control of the major histocompatibility complex (MHC) class I regulatory sequences show low level expression of IL‐4 in all organs investigated. Several weeks after birth the animals develop thymus hypoplasia with a loss of CD4 + CD8 + double‐positive cells and a relative increase in the mature population, especially, and in contrast to previously published lines, the CD4 + single‐positive cells. In the periphery, T lymphocytes eventually decline, CD8 + cells being more strongly affected. Many of the residual T cells exhibit the CD44 high Mel‐14 low phenotype of antigenically experienced T cells. B cells also show an activated phenotype with respect to size, MHC class II and CD23 expression, are more readily stimulated by anti‐μ F(ab′) 2 antibodies than are B cells from control littermates, and show a higher spontaneous and antigen‐induced production of IgG1 and IgE.