Enhancement of T cell immune response to lymphoma cells by CD28/CD80 alternative pathway

The aim of this study is to determine whether myeloma and lymphoma tumor cells can function as efficient antigen presenting cells (APC) to enhance the co-stimulation of T cells. The expression and function of T cell activation-related molecules, especially CD80, CD28, CD40 and CD40 ligand (CD40L), were studied on nine human myeloma cell lines (HMCL) and two B lymphoma cell lines. In the case of myeloma cell lines, the cells generally lacked CD80 antigen and expressed a heterogeneous CD40, and the expressions of CD40 and CD80 molecules could not be induced by either CD28 stimulation or CD40 ligation. Conversely, in the two B lymphoma cell lines, tumor cells expressed both CD80 and CD40 to some extent. CD28 stimulation could obviously increase the expression of CD80 , CD40 and some adhesion molecules, and therefore generate a more efficient anti-tumor cell immunity. In conclusion, CD28 stimulation combined with CD40 antibody or soluble CD40 ligand may be a promising immunotherapeutic approach to B lymphom