Arthritis in mice: allogeneic pregnancy protects more than syngeneic by attenuating cellular immune response

We tested the hypothesis that collagen induced arthritis benefits more from allogeneic pregnancy than syngeneic pregnancy.

Arthritis was induced in female B10.RIII (H-2r) mice by injecting bovine type II collagen. Female mice were subsequently paired, one group with q-haplotype males (B10.Q) and the other with r-haplotype males (B10.RIII). The effect of q- and r-haplotype was measured by determining the acute phase reactant serum amyloid A (m-SAA), bovine anti-collagen type II antibodies (a-CBII), and the ratio of CD4/CD8 T lymphocytes during pregnancy and after delivery. Clinical assessment of arthritis was also performed.

The number of mice with maximum severity of clinical arthritis was significantly higher in the syngeneic group (11/20 vs 5/21; p = 0.04). Although we noted that in the allogeneic group the females had had a significantly higher level of a-CBII during pregnancy (p = 0.02), we also found that the ratio of CD4/CD8 was higher in the syngeneic group even if it was measured during (p = 0.04) or after gestation (p = 0.05). Taking into account all the cases of arthritis initiated in the post-gestational period there was no difference in m-SAA or in a-CBII between the 2 groups, but the ratio of CD4/CD8 was higher in the syngeneic group measured during (p = 0.03) or post gestation (p = 0.02).

Allogeneic pregnancy benefits more than syngeneic pregnancy by attenuating the cellular immune response, and the ratio of CD4/CD8 indicates the attenuation of cellular immunity when measured during gestation or post partum.