Immunology of HIV and pregnancy. The effects of each on the other.

Infection with HIV may significantly affect the human immune response. Depletion of CD4 T cells directly or indirectly results in global immune dysfunction, including both cellular and humoral components of the immune system. Ongoing viral replication leads to progressive immune destruction despite apparent clinical latency. The end result, if left untreated, is CD4 T-cell depletion, severe immune compromise, opportunistic infection, and eventual death. Pregnancy has been purported to induce an altered immune state to protect the fetus from immune rejection that may leave the mother with impaired immunity. This theoretical risk has been overemphasized, and, in fact, only limited data suggest that certain infections may have worse presentations and outcomes during pregnancy. The mother maintains immunocompetence throughout gestation and is not overwhelmed with opportunistic infection. Women infected with HIV may experience some decline in CD4 T-cell percentages and possibly in function. It is not clear whether any of the effects will significantly affect long-term outcome. Infection with HIV may predispose pregnant women to a variety of adverse pregnancy outcomes, including preterm labor, prematurity, low-birth-weight infants, postpartum endometritis, and other infectious morbidity. Larger controlled studies are necessary to determine the frequency of these adverse outcomes and whether they will predominantly affect the severely immunocompromised HIV-infected pregnant women.

The immunology of HIV disease and pregnancy and possible interactions.

HIV infection may impair a large portion of the human immune response. Infection of CD4+ T cells results in depletion of this population, leading to dysfunction of T-cell-dependent activities. Numerous other immune functions are directly or indirectly impaired, including the function of CD8+ T cells and decreases in total lymphocytes, IL-2 secretion, IL-2R expression, proliferative response to mitogens, NK activity, ADCC, and several other measures. Immune alterations seen in normal pregnancy include decreases in CD4 and T cells, the proliferative response to mitogen, IL-2 secretion, and NK activity. These changes are largely cellular and usually are not apparent clinically. Normal pregnant women are immunocompetent. When pregnancy is complicated by asymptomatic HIV infection, the obstetric outcome does not seem to be adversely affected. Preliminary studies show that the course of HIV disease may not be adversely affected in these women, but this matter is the subject of intense investigation.