Popliteal Lymph Node Assay, Secondary Reaction
The secondary PLNA (reviewed in Pieters et al. (2002), Pieters and Albers (1999), Goebel et al. (1996), Ravel and Descotes (2005)) aims at determining a secondary T-lymphocyte response to a low-molecular-weight chemical by injecting the chemical subcutaneously into one hind footpad of already-sensitized mice or rats. The administered dose has to be small enough not to elicit a primary immune response in nonsensitized animals, i.e., it should not suffice for stimulation of naïve T lymphocytes. The immune response against the injected chemical or antigen is quantified by analyzing one or more parameters of the draining popliteal lymph node (PLN), such as PLN weight, PLN cell number, cell surface marker expression on PLN cells, or PLN cell proliferation measured, for example, as 3H-methyl thymidine incorporation.
In the direct PLNA, a single injection of the test chemical is administered...