Lf - Limit of Flocculation for Tetanus antigen amount

[Gunther Schadow]

This unit is being requested by CBER for "quantity of toxoid as assessed by flocculation".

We are still waiting for a definition.

But likely it is just another arbitrary unit. So we can assign [Lf].

I have given push-back, to get thinking about SI units instead, but of course this won't happen any time soon.

Electronic listing depends on this, so we will have to proceed.

[Gunther Schadow]

Here is a decent definition:

The unit “Lf” is called the "Limit of Floculation" or "limes flocculationes". It is based on an antigen-antibody precipitation assay and used predominantly for Tetanus and Diphteria toxoid quantification (but other antigens as well.) The limes flocculationis is the amount of an antibody (measured in international units) which equilibriates the antigen present such that the antigen-antibody complexes precipitate (flocculate). [Source: Schwanig M. Diphtherie und Tetanus: Wie haufig braucht der Mensch Boosterdosen? in: Alte und neue Impfstoffe in Deutschland. Grundlagen fur kunftige Entscheidungen, 27-33, 2001, Infomed Medizinische Verlagsgesellschaft mbH, Berlin.

[Gunther Schadow]

done [33172]