Which proteins are coded by MHC class III genes?

MHC class III genes are involved in the immune response and have a variety of functions, including the coding of proteins that play crucial roles in the complement system. These proteins are essential for enhancing immunity, particularly in opsonization, lysis of pathogens, and promotion of inflammation. The complement system, part of the innate immune response, helps clear pathogens and damaged cells from the body.

The other choices can be put into context to clarify their relationship to the MHC class III gene products. Antibodies are produced by B cells and are not coded by MHC class III genes; instead, they are the result of a different genetic mechanism. Cytokines, which are signaling proteins important in cell communication during immune responses, are also not coded by MHC class III genes although some are related to immune function. Class I MHC proteins are primarily involved in presenting peptide antigens to CD8+ T cells and are specifically coded by MHC class I genes, not class III.

Thus, the significant role of MHC class III genes in producing complement proteins is key for understanding their function within the immune system.