Abstract: The present invention provides a process for determining the quantitative and qualitative profile of the repertoire of a given type of an immunoglobulin (Ig) heavy chain expressed by a B lymphocyte population present in a tissue sample, and kits and uses thereof. It also provides a set of VH forward primers associated with a CH reverse primer, which are respectively capable of specifically hybridizing in stringent conditions with the nucleic acids encoding the variable segments of Ig heavy chains and with the constant segment of a given type of Ig heavy chain, such as preferably an IgM, IgG, IgE or IgA heavy chain. Methods for the in vitro diagnosis of a condition associated with an abnormal expression of the repertoire of a given type of Ig heavy chain, and for the in vitro follow-up of a treatment of such a condition, are also included herein.