The evidence on the possible interleukin-1 alpha tuftsin competition

It was demonstrated by the experiments performed in vivo in mice (peripheral blood leukocyte number determination), and in vitro on mouse thymocytes (autologous rosette forming cell number determination) that tuftsin (Thr-Lys-Pro-Arg), a natural phagocytosis-stimulating factor, inhibits the action of interleukin 1 alpha. This effect is interpreted by us in the terms of structural correspondence between tuftsin and "retro-tuftsin"-like sequence 210-213 of the IL-1 alpha peptide chain. The analysis of tertiary structure shows that this sequence is localized in the exposed fragment of the IL-1 alpha molecule, probably responsible for the interaction with the receptor.