In vivo priming of mice with antigen and lipid A bestows proliferative ability on peritoneal exudate T cells in response to antigen or anti-alpha beta TCR antibody in the absence of macrophages in vitro: accessory function of NK cells

Highly purified T cells of mice that have been primed in vivo with horse re d blood cells (HRBC) and lipid A, but not with HRBC alone, can proliferate in vitro in response to HRBC or anti-alpha beta T cell receptor (TCR) antib ody without macrophages. The mechanism of proliferation without macrophages was investigated. Mice were primed with HRBC and lipid A together or with HRBC alone 10 days in advance, and the peritoneal exudate cells (PEC) were obtained. Purified T cells were obtained by treating the PEC by the followi ng series of procedures: nylon fiber column-passage, antibody (anti-Ia, ant i-Mac-1, and LR-1) treatments with complement (C), and a G-10 column-passag e. Cell proliferation was assessed by [H-3]-thymidine ('TdR) incorporation into the cultured T cells in response to HRBC or anti-alpha beta TCR antibo dy. The proliferation of T cells [T(HRBC+lipid A)] that had been prepared f rom the PEC of the mice primed with HRBC and lipid A increased dose-depende ntly to these stimulants, but T cells [T(HRBC)] prepared from PEC of mice p rimed with HRBC showed little or no proliferation in response to them. The expression pattern of a memory cell marker, CD44, on the cell surface of T( HRBC+lipid A) was obviously different from that on T(HRBC). The proliferati on of T(HRBC+lipid A) was suppressed when the cells were cultured in the we lls coated with hyaluronate, a ligand for CD44, or cultured after a previou s treatment with anti-CD44 (IgG2a) and anti-IgG2a antibodies. In contrast, the proliferation of T(HRBC) was up-regulated in culture under the same con ditions. Proliferative responses of T(HRBC+lipid A) to anti-alpha beta TCR antibody were enhanced in the wells coated with anti-CD28 antibody. These f indings indicate that the proliferation of T(HRBC+lipid A) was not only sup ported by a stimulation of TCR but also regulated by another stimulation vi a ligands such as CD44 and CD28. The proliferation of T(HRBC+lipid A) was a bolished when the cells were pretreated with AsGM1 antibody or anti-CD80 an tibody and C. These findings indicate that the in vivo priming of mice with HRBC and lipid A generates a memory T cell population that is capable of p roliferating without help of macrophages, but with NK cells, when stimulate d their TCR.