Autoimmunity,hyporeactivity to T cell mitogens and lymphoproliferative disorders following neonatal induction of transplantation tolerance in mice

We have reported that, in A/J (A) (H-2^a) mice, a partial tolerance to C57BL/10ScSn (B10) (H-2^b) skin allografts and a high incidence of lethal lymphoproliferative disorders (LPD) can be induced by the neonatal i.v. injection of 2 × 10⁷ semiallogeneic (B10 × A)F₁ spleen cells (SC) (Végh, P., Baranyi, L. and Jánossy, T., Cell. Immunol. 1990. 129: 56). In this study, we show that the incidence and mortality of LPD were continuously growing from 1 month of age until the end of the experiment at 1 year (64% and 36%, respectively). Based on histology, 27% of the diseased mice suffered from lymphoid malignancies. In the remaining cases (73%), reactive histopathological changes were seen in the spleen, lymph nodes (LN), liver and kidneys. The proportion of CD4⁺Tcells in the spleen and LN as well as that of splenic B cells decreased, while the percentages of mature and immature myeloid cells doubled. The total cell number of each (sub)population, however, was elevated in both lymphoid organs. The cells taking part in the lymphoproliferation were of host (A) and not of donor (F¹) origin. Preceding the development of apparent LPD, the SC, LN cell and thymus cell suspensions of 1-month-old tolerized mice showed reduced in vitro proliferative responses to cell and T cell-dependent B cell mitogens (Con A or PWM), while their reactivity to aT cell-independent B cell mitogen (lipopolysaccharide) was essentially unimpaired. This hyporeactivity seems to be functional, because neither histology nor immunophenotyping by flow cytometry revealed significant alterations in the spleen and thymus of such animals, apart from a slight reduction in the ratio of CD4+/CD8⁺ T cell subpopulations in the spleen. The in vivo T cell-mediated immune response of the tolerized mice was practically normal to third party CBA/Ca (H-2^k) allografts. Antithymocyte autoantibodies (ATA) were detected in the sera of 76% of the tolerized mice at 1 month of age (i.e., even before the mass appearence of LPD). ATA as well as antinuclear Ab were present in 65% of the adult tolerized mice, independently of the presence of LPD. Taken together, in A mice neonatally injected with (B10 × A)F₁SC, a partial, specific allograft tolerance and a chronic host-vs.-graft disease-like syndrome developed. The latter is manifested in hyporeactivity to T cell mitogens, development of autoantibodies and, subsequently, in progressive LPD and lymphoid malignancies.