Oliveira, Geraldo Gileno de Sá “Documento produzido em parceria ou por autor vinculado à Fiocruz, mas não consta à informação no documento”.Brazilian Council for Development of Research and Technology (CNPq.).New Zealand Black (NZB) mice spontaneousl2,. develop autoimmune haemolytic anaemia as the result of production of autoantibodies to erythrocytes. We have recently shown that antibodies to CD4 prevent the development of erythrocyte autoantibodies in young mice (Coombs' negative). In spite of this inhibition of erythrocyte autoantibody production, the anti-CD4-treated mice show a precocious and severe anaemia. Balb, c mice treated with the same protocol do not develop anaemia. Our results suggest that er.~- thropoiesis in NZB mice is particularly sensitive to depletion of CD4 + T cells.