Subpopulations of CD4+ cells in lpr/lpr mice: differences in expression of T cell receptor/CD3 complex and proliferative responses

Abstract

CD4⁺ cells from autoimmune‐prone C57BL/6 lpr/lpr mice contain two subpopulations, B220 CD4⁺ and B220⁺ CD4⁺ cells. Highly purified B220 CD4⁺ cells from C57BL/6 +/+ and lpr/lpr mice were examined by comparing functional characteristics and expression of cell surface antigens and T cell receptor (TcR)/CD3 complex. Both Ipr B220⁺CD4⁺ and B220⁺CD4⁻ CD8 cells, most of which were PgP‐1 positive, expressed TcR/CD3 complex on the cell surface at lower level as compared with B220 CD4⁺ cells of age‐matched normal mice. In addition, the B220 CD4⁺ cells were heterogeneous on the basis of surface expression of PgP‐1 and CD3 antigens. Normal levels of TcR C_x‐, C_β‐ and V_β8‐specific mRN A were found in the B220 CD4⁺cells and B220⁺ CD4⁺ cells as compared with normal B220⁻ CD4⁺ cells, while V_β8‐specific mRN A was preferentially expressed only by B220⁺ CD4CD8 cells. Either B220⁺ CD4⁺ cells and B220⁺CD4⁻ CD8⁻ cells Tailed to respond to anti‐CD3 monoclonal antibody (MoAb) as assessed by proliferative responses and production of interleukin‐2 (IL‐2). However, appreciable levels of reactivity to anti‐CD3 MoAb were detected in the B220 CD4⁺ cells, although the responsiveness of this subset to such stimuli were reduced, compared with those of normal control. These results indicate that the B220⁻ CD4⁺ cells in Ipr mice are phenotypically and functionally distinct from normal B220 CD4⁺ cells.