Any process of gene rearrangement in which one immunoglobulin heavy chain constant coding region is exchanged for another, with the loss of the intervening region, resulting in an altered profile of effector molecule interactions for the antibody produced. During this process the variable coding region of the heavy chain remains unchanged, thus retaining antigen specificity. Immunoglobulin class switch recombination is involved in the maturation of an immune respone toward a particular antigen. [ ]