A monoclonal antibody (L21-6) recognizing an invariant chain expressed on the cell surface in rats with the exception of the BN (RT1n): a study of tissue and strain distributions.

I T IS an established fact that class II molecules play a crucial role in the initial recognition of foreign antigens.1.2 Exogenous antigen peptide and these class II molecule a-, /3-chain complexes are recognized by the T-cell receptor. On the other hand, in cytoplasm, the invariant chain, which is a nonpolymorphic peptide, binds the class II molecules and prevents the binding of endogenous peptides.3 In addition, it has been reported that an invariant chain is expressed on the cell surface in the human4 and mouse,s but .js not reported in the rat. The distribution of the invariant chain on the cell surface is very similar to that of class II molecules, but the invariant chain was observed without class II molecules in certain cells. The differential expression of class II and invariant chain with interferon-'Y treatment in the mouse was reported.f> Therefore, we developed a unique monoclonal antibody (MAb), L21-6, recognizing an invariant chain on the cell surface in the rats and studied the tissue and strain distributions.