Cytokines are often thought of as short range, short half-life molecules. This view may now be challenged by recent findings that indicate that alpha 2-macroglobulin and antibodies to cytokines may alter cytokine kinetics in vivo. alpha 2-Macroglobulin, one of the major proteins in serum, can bind a wide range of physiologically important molecules. As Keith James reviews here, the interaction between alpha 2-macroglobulin and a number of cytokines has recently come under scrutiny, revealing a new and potentially important mechanism for the modulation of cytokine activity, while in the following paper a modulatory role for anti-cytokine antibodies is considered.