On the site of rat reagin formation.

Normal and splenectomized rats were injected by the intravenous route with small amounts of soluble antigen (egg albumin) or particulate antigen (toad red cells) plus Bordetella pertussis vaccine and bled at various times afterwards. The reaginic antibody was assayed by passive cutaneous anaphylaxis using a 72-hour period between antibody and antigen injection and the haemolytic antibody by determining the highest dilution of serum giving complete lysis in presence of complement. It was observed that although splenectomized animals responded with a very much diminished production of haemolytic antibody their production of reaginic antibody was very similar to that of the non-splenectomized animals. It is suggested that the spleen plays little or no role in the production of rat reaginic antibody.