Immunologic and inflammatory responses during pregnancy.

Rheumatoid arthritis commonly improves markedly during pregnancy, and it has been suggested that this reflects a decrease in immunological or inflammatory effector mechanisms. We elicited a delayed type hypersensitivity (DTH) response to Burro RBC, by injection of primed lymphocytes and antigen into murine footpads. The swelling induced in footpads of pregnant mice was not significantly different from that seen in controls, nor was the response to a non-immunologic inflammatory stimulus, carrageenan, decreased in pregnant mice. On the other hand, a defect in the priming or induction phase of a primary DTH response was impaired in pregnancy, but whether this is relevant to the pregnancy induced remission of rheumatoid arthritis remains to be demonstrated.