Changing incidence of positive direct Coombs test in inbred NZB-BL mice.

The. inbred NZB/BL mouse has been shown by Bielschowsky, Helyer, and Howie (1959) to develop auto-immune haemolytic anaemia spontaneously, and this disorder has been considered to be genetically determined (Holmes and Burnet, 1966). Burnet and Holmes (1962) described a characteristic thymic change in this 'auto-immune' strain of mice; and certain renal lesions have been noted (Holmes and Burnet, 1963). The haemolytic anaemia in these mice has been associated with the presence of at least two different red cell auto-antibodies (Barnes and Tuffrey, 1966a). Both a positive direct Coombs test (DCT) antibody specific to mouse (Holmes and Burnet, 1963) and also an antibody which cross-reacts with mouse and human red cells (AHR) (Holborow, Barnes, and Tuffrey, 1965) have been described. Other auto-antibodies have been noted and include the LE cell factor (Helyer and Howie, 1961) and antinuclear factor (ANF) (Norins and Holmes, 1964; Holborow et al., 1965). Like other workers (Holmes and Burnet, 1963; Norins and Holmes, 1964; East, Sousa, and Parrott, 1965; Miyasato, Marraligod, and Pollak, 1967), we have described the different age and sex incidence of certain of these spontaneously developing auto-antibodies since the original description of red cell auto-antibodies in the NZB/BL mouse by Bielschowsky et al. in 1959. Using adoptive immunization techniques, we have shown the direct effect of the two red cell auto-antibodies in increasing in vivo red cell breakdown in the anaemic NZB/BL (Barnes and Tuffrey, 1966a, b). However, we have been unable to suggest any relation between the occurrence ofANF and disease in the NZB/BL (Holborow et al., 1965). The finding of a high incidence of ANF in several 'normal' mouse strains (Barnes and Tuffrey, 1967) and our inability to relate the surprisingly high incidence of ANF in the NZB x CFW cross to any