Cardiovascular adaptations of pregnancy in T and B cell-deficient mice.

The pathophysiology of gestational hypertensive disorders is incompletely defined. T lymphocytes are implicated. Both T and natural killer (NK) cells express RAS and, in implantation sites, NK cells are highly enriched. We hypothesized that T cells and/or NK cells contribute to circulatory control during pregnancy. Using radiotelemetry of arterial pressure, heart rate, and activity, mice without T and B cells (genotypes BALB/c-Rag2(-/-) and NOD.scid) were examined at baseline and across pregnancy. These strains differ in NK cell competency, with Rag2(-/-) being normal and NOD.scid impaired. Circulatory features differed between these inbred strains. Rag2(-/-); had blood pressure responses to pregnancy that did not differ from congenic normal mice. NOD.scid had higher midgestational blood pressure compared with normoglycemic NOD mice (3-5 mm Hg greater than NOD; P < 0.004). In comparison to controls, both T and B strains had much higher heart rates after first trimester that did not remit until parturition (>30 bpm greater than control; P < 0.0001). NOD.scid had additional anomalies, including 90% depletion of circulating NK cells and elevated (57%) proliferation of uterine NK cells within implantation sites. These data demonstrate immune control of midgestational heart rate and suggest NK cells contribute to midpregnancy regulation of mean arterial pressure.