Reversible cell labelling with conjugates having two releasable binding sites

1. A method for detecting a target moiety in a sample of biological specimens by:

a) providing at least one conjugate with the general formula (I)

A n -P-B m -C q -X o   (I)

wherein

A: is an antigen recognizing moiety A;

P: is an enzymatically degradable spacer;

B: is a first binding moiety;

C is a second binding moiety;

X: is a detection moiety;

n is an integer greater than 1 and less than 100;

m, q, o are integers between 1 and 100, and

wherein B and C are non-covalently bound to each other and A and B are covalently bound to P, and wherein the antigen recognizing moiety A is a Fab fragment of an antibody against an antigen and wherein the enzymatically degradable spacer is a polysaccharide;

b) labelling the target moiety recognized by the antigen recognizing moiety A with the at least one conjugate with the general formula (I);

c) detecting the labelled target moiety via detecting moiety X o ;

d) cleaving C q -X o by disrupting the non-covalent bond between B m and C q from the labelled target moiety; and

e) cleaving the binding moiety B m from the labelled target moiety by enzymatically degrading spacer P thereby removing A, B, C, P, X form the target moiety.

2. The method according to claim 1 , characterized that disrupting the non-covalent bond between B m and C q in step d) is performed by adding a release agent that binds to the first binding moiety B, thereby displacing the second binding moiety C and/or by adding a release agent that binds to the second binding moiety C, thereby displacing the first binding moiety B.

3. The method according to claim 1 , characterized in that step d) and e) are performed simultaneously.