Titers of Antilymphocytic Sera Determined by Immunofluorescence

Abstract

The antibody titers of canine antilymphocytic sera from the horse and rabbit were measured by indirect immunofluorescence by reacting the antilymphocytic sera with canine lymphocytes, then attaching labeled antihorse globulin (IgG) to the lymphocyte-antibody complex. This method is sensitive and specific, and the titers correlate closely with titers obtained by the cytotoxicity test. It has practical advantages. It is complement-independent and obviates the need for viable cells. Many smears can be prepared from a single cell preparation, air-dried, and stored for future use. The membranes, the antigenic parts of the cells, fluoresce light green and are quite distinguishable from the nonfluorescing nuclei when viewed with blue-light fluorescence through either a brightfield or a darkfield condenser. Because this reaction is an expression of an antigen-antibody union in a nonviable state, if adequate controls are used to detect nonspecific reactions, false-positive findings are eliminated. (However, in this study nonspecific reactions were not found.)