Pharmaceutical compositions for the modulation of the immune reaction of warm blooded animals that are derivatives of the 2-oxindole-3-acetic acid or the 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid are described, and whereby the derivatives can optionally be in an equilibrium with each other. The derivatives included in the pharmaceutical compositions comprise those compounds which are already described in the literature and also new compounds. Furthermore, new derivatives of the the 2-oxindole-3-acetic acid and the 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid are described, particularly also the the pure antipodes of the mixture of enantiomeres of the 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid.