Demonstration of antibodies to chlorophenothiazine derivatives

Antibody to 2-chloro-10-(2-carboxyethyl)-phenothiazine (CECP) was produced in rabbits by immunization with the hapten-BSA conjugate. The titer of antibody was determined by passive hemagglutination (PHA) using erythrocytes coupled with the CECP-protein carrier. Results from inhibition tests using structurally related (CECP, CPZ, PCPZ, CMP) and almost unrelated haptens (DDA, RF) strongly suggested that both the side chain and the nucleus of the haptens are important in determining the specificicity of immunological reactions. 18 sera from psychiatric patients administered phenothiazine derivatives for a long time as well as 20 control sera from healthy individuals were then tested for their reactivity to CECP. Of patients' sera, 12 had detecable hemagglutination titers (1:8 or greater), while all of the normal human sera were negative. The PHA activity was contained in euglobulin fraction and was specific in the inhibition tests. From these results, the activity to CECP in patients' sera was supposed to be specific antibody.