Hyperimmunoglobulinaemia, T-cell deficiency and plasmacytosis in RFM mice with host versus graft disease induced by the perinatal inoculations (T6XRFM)F1 spleen cells.

Host versus graft (HVG) syndrome may be induced in parental strain mice by perinatal inoculations of F1 hybrid spleen cells. The principal manifestations of the disease include thrombocytopaenia, intravascular fibrin deposits, intestinal haemorrhage, hepatic infarcts, lymphosplenomegaly and renal disease. Immune complexes have been shown to be the cause of the renal lesions, and have been implicated as the triggers for disseminated intravascular coagulation. In the present studies of RFM mice perinatally inoculated with (T6 x RFM)F1 spleen cells (RFM/(T6 x RFM)F1 mice), quantitative determinations of serum immunoglobulins (Ig) revealed marked elevations of IgG1, IgG2, IgA and IgM. Electrophoretic analyses revealed the polyclonal pattern which typically follows chronic antigenic stimulation. However, IgG1 levels which reached 29 to 72 times control values suggested disruption of homeostatic mechanisms which control circulating Ig levels. Because antibody responses to histocompatibility antigens were present only occasionally, and then in low titre, it seemed unlikely these antigens were the principal causes of hypergammaglobulinaemia and plasmacytosis. Morphological studies indicated that the elevated levels of Ig seen in end-stage HVG syndrome correlated well with marked plasmacytosis, the third morphological finding in a sequence that included the precocious development of germinal centres and subsequent depletion of thymic-dependent (T) lymphocytes. The fact that spleen cells from RFM/(T6 x RFM)F1 mice were severely impaired in their capacity to cause graft versus host disease in related (T6 x RFM)F1 and unrelated C3H mice provided strong evidence that the HVG reaction resulted in T-cell depletion, rather than specific immunoincompetence.