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Abstract: Red blood cell allo-immunization is the immune response of an individual to foreign red blood cell antigens not present on the surface of their own cells. The aim of that paper is to clarify the different factors influencing the antibody response against red blood cell antigens. [Copyright &y& Elsevier]

The article presents questions and answers related to red blood cells for patients who are negative for a high-frequency antigen including the definition of a rare donor, problems encountered in finding compatible red blood cells (RBC) for patients, and whether countries have a national panel of rare donors and/or a national bank of frozen (RBC) units from such donors.

Abstract: A rare blood group is usually defined as the absence of a high prevalence antigen or the absence of several antigens within a single blood group system, if its prevalence in France is 4/1000 or less in the general population. An individual with a rare blood phenotype can develop a naturally-occurring or immune antibody corresponding to his rare specificity. In case an extremely low stock of compatible blood is available at the national level, a so-called “transfusion deadlock” is described. Most of the individuals with a rare blood group are coincidently identified when a routine pretransfusion testing or pregnancy follow-up is performed, if the antibody(ies) corresponding to the rare specificity is(are) present. Other individuals are discovered following a systematic red cell typing, or family investigations in siblings. One hundred and twenty-one rare blood specificities and 42 rare blood genotypes are currently defined at the French National Reference Laboratory for Blood Groups (CNRGS–Paris). The French national registry of individuals with a rare blood phenotype/genotype includes about 9600 people, who are urged to regularly donate blood for the National Rare Blood Bank. This bank, based on a homologous blood transfusion program, is in charge of the long-term storage of rare frozen blood units, that can only be delivered after receiving authorization from the CNRGS. The global and individual care management of the individuals with a rare blood group, concerning potentially several hundred thousand people in France, requires a close cooperation between all the protagonists within the transfusion chain. [Copyright &y& Elsevier]

Polyclonal B cell activity in systemic lupus erythematosus (SLE)may be under T cell control. The use of nitrocellulose irnmunoblots for the analysis of recognition by peripheral blood lymphocytes of nucleoplasmic proteins in SLE patients led to the characterization of significant proliferative responses to 68K (UI RNP): SS-B: B-B' and D (Sm) antigen in 15 of 20 patients. Variations of proliferative response were parallel to disease activity over a follow-up period of ⩾ 6 months. conferring some prognostic value to the assay of lymphocyte response to nucleoplasmic antigens. The pattern of reactivity differs from the corresponding serum antibody profile, and purified T cell suspensions ( >95% pure) were shown to proliferate in response to soluble nucleoplasmic antigens, indicating that T and B cell repertoires against nucleoplasmic proteins may differ. This suggests that activated helper T cells contribute to the fine modulation of B cell reactivity to subcellular particles to determine the particular antibody profile of the patients. [ABSTRACT FROM AUTHOR]