Action of dextran sulfate as a direct and general B cell mitogen

Dextran sulfate (DS‐500) significantly stimulates the in vitro immune response against thymus‐dependent antigens in the absence of T cells. The stimulation of antibody production takes place both in the presence and absence of antigens. Dextran sulfate leads to increased cell division as measured by [3H]thymidine incorporation; the amount of TCA precipitable radioactivity is greater in the absence of T cells than in their presence. It is suggested that the stimulatory effect of DS‐500 is due to its function as a general and direct B cell mitogen.