The spontaneous development of immune complex type glomerular lesions in outbred mice is dependent on environmental factors and sex.

To investigate the role of environmental factors in the spontaneous development of immune complex glomerulonephritis in the mouse, follow-up studies of various immunological parameters and of kidney lesions have been done in male and female outbred OF1 mice housed from birth to four months of age in two different conditions: (a) in a conventional animal house; (b) in a "controlled" animal house designed for long-term studies on nude mice. Female mice housed under conventional conditions develop mild to intense glomerular lesions with granular deposits of immunoglobulins and C3 after two months of age. The appearance of these lesions is correlated with a sharp increase of various IgG subclasses levels at two months of age. Female mice housed under "controlled" conditions do not show such an increase and have only scarce to mild lesions until four months of age. In male mice, similar observations are done but the differences in immunological parameters and in histopathological findings between the two groups of mice according to the housing conditions are less noticeable. The environmental factors which are involved in the development of these immune mediated lesions are not known; it is hypothetized that infectious agents play a role. This study emphasizes the importance of housing conditions and of sex in immunopathological investigations in the mouse and the possible bias these conditions may introduce, in some experiments.