Synthesis of an immunogenic conjugate and of two 125I-labelled derivatives of the "facteur thymique sérique".

[4-Aminobenzoyl-Gln1]FTS was synthesized from a suitably-protected derivative of the "facteur thymique sérique" (FTS). It was diazotized and coupled to bovine serum albumin, yielding an immunogenic conjugate in which all the functional groups of the peptide remained intact. [4-Aminobenzoyl-Gln1]FTS and another synthetic ćompound, [3-(4-hydroxyphenyl)propionyl-Gln1]FTS, were 125I-labelled. The binding of these radioactive peptides of the anti-FTS antibodies obtained with our immunogenic conjugate was inhibited by unlabelled FTS.