Antigens And Antibodies

To determine which pair of antibodies contains the 'J-chain' in their multimeric form, let's examine the characteristics of each antibody type mentioned in the options.

1. IgA: Immunoglobulin A (IgA) exists primarily in two forms: monomeric and dimeric. The dimeric form of IgA contains a J-chain, which is essential for its polymerization and transport across epithelial surfaces into mucosal areas.
2. IgM: Immunoglobulin M (IgM) is generally found in its pentameric form in the bloodstream. The pentameric structure is maintained by a J-chain, which is critical for stabilizing the complex and facilitating its function in the immune response.
3. IgE: Immunoglobulin E (IgE) is a monomer and does not utilize a J-chain in its structure.
4. IgD: Immunoglobulin D (IgD) is another monomeric antibody and does not require a J-chain for its structure or function.
5. IgG: Immunoglobulin G (IgG) is the most abundant circulating antibody and is also monomeric, thus not associated with a J-chain.

From this analysis, it is clear that only IgA and IgM have structures involving the J-chain, specifically in their dimeric and pentameric forms, respectively.

Therefore, the correct pair of antibodies that contain the 'J-chain' in their multimeric form is IgA and IgM.