Immune cell defects affect bone remodelling in osteopetrotic op/op mice.

ABSTRACT

The aim of the present work was to further characterize immunological defects in osteopetrosis. The op/op mutant mouse is of particular interest since a marrow cavity develops spontaneously in older animals. The interleukin production (IL-1, IL-2, IL-3, IL-4, IL-6), the presence of macrophage differentiation antigens and the evolution of the bone lesions were studied in osteopetrotic and normal mice. Low levels of IL-1, IL-3 and IL-4 were observed at the age of 6 weeks in the op/op mice. However, at 22 weeks of age, the level of IL-1 and IL-4 returned to normal value in these op/op mice whereas the level of IL-3 remained partially decreased at the same age. Furthermore, macrophage expression of MAC-2 antigen, reduced at 12 weeks of age was found to be normal 10 weeks later. These immunological defects and their recovery seems to be concomitant with the healing of the bone lesions.