Cell-mediated immunity to cytomegalovirus in patients receiving immunosuppressive therapy

The prevention of cytomegalovirus disease in renal transplantation

Primary cytomegalovirus (CMV) disease can be prevented in renal transplant recipients with the use of either CMV hyperimmune globulin (CMVIg) or acyclovir. Started within 72 hours of transplantation and continued for 16 weeks posttransplant, CMVIg decreases the incidence of primary CMV disease from 60% to 21%. Acyclovir administered preoperatively and for 3 months thereafter decreases the incidence of CMV disease from 29% to 8% and is the most cost-effective therapy. The effectiveness of these preparations in preventing CMV reinfection or reactivation has not been established. The utility of therapies other than CMVIg or acyclovir for the prevention of CMV disease has not been proven; CMV vaccination is ineffective, polyvalent immunoglobulins require further study, and interferon alpha (IFN-alpha) has been associated with frequent irreversible rejection reactions and therefore should not be used for CMV prophylaxis. Although further investigation is necessary, patients at risk for primary CMV disease should receive prophylactic therapy with either CMVIg or acyclovir.

Towne-vaccine-induced prevention of cytomegalovirus disease after renal transplants

91 renal transplant candidates were randomised to receive Towne strain cytomegalovirus (CMV) vaccine or placebo at least 8 weeks before transplantation. The vaccine was well tolerated and there was no vaccine virus excretion. Serological and cellular immune responses developed in most vaccines but were lower in the transplant patients than in healthy volunteers and some of the seronegative patients failed to mount responses. CMV infection occurred in most of the seronegative vaccine-treated or placebo-treated patients who received kidneys from seropositive donors, but the illnesses were less severe in the vaccines than those in similarly exposed placebo-treated patients. Vaccine-treated patients who received kidneys from seronegative donors did not excrete virus, and therefore the vaccine virus was not reactivated from a putative latent state despite immunosuppression at the time of transplantation.

Longitudinal studies of cytomegalovirus-specific cell-mediated immunity in congenitally infected infants

Characteristics of specific cell-mediated immunity in infants with congenital cytomegalovirus (CMV) infection were studied by in vitro lymphocyte transformation test, using the whole blood culture technique. Subjects were 6 symptomatic congenitally infected infants, 11 asymptomatic congenitally infected infants, 3 postnatally infected infants, and 5 CMV-free infants. Among them, three symptomatics and seven asymptomatics were studied temporally, together with three postnatally infected infants and five controls. In the congenitally infected group, 18 of 47 (38%) specimens proved to be negative in terms of stimulation index values. Studies of temporal changes in CMV lymphocyte transformation tests revealed that in the postnatally infected group, the response turned positive in accordance with the appearance of CMV viruria and remained positive afterwards. In the congenitally infected group, the delay in development of positive reaction followed initial negativity, a phenomenon conspicuously observed in the symptomatic subjects. No significant difference was seen in phytohemagglutinin-induced lymphocyte transformation tests among congenital, postnatal, and control groups.

Cell-mediated immunity to cytomegalovirus in pregnant women

Employing the techniques of in vitro lymphocyte transformation (LTF) and complement fixation, cell-mediated immunity (CMI) and antibody to cytomegalovirus (CMV) were studied in pregnant and nonpregnant women. The LTF activity was determined by the whole blood microassay using four strains of CMV (AD-169 and its early antigen [EA], Davis, Veca, and Towne strains), and phytohemagglutinin (PHA). Lymphocyte transformation response to specific CMV antigens at 11-30 weeks of gestation and to nonspecific mitogen (PHA) in all pregnant and postpartum women were found to be significantly depressed compared with the nonpregnant women. The lower LTF responses to CMV antigen and PHA were found in specimens taken from pregnant women at 21-30 weeks of gestation. There were no significant differences in the mean complement-fixing (CF) antibody titers and the percentage of E-rosette-forming T lymphocytes between subjects in various stages of pregnancy. In addition, concanavalin A (Con A)-generated suppressor T cell activity was evaluated in pregnant and nonpregnant women. The suppressor effect of Con A-activated lymphocytes in the pregnant women was somewhat higher than in nonpregnant women. These observations suggest that CMV-specific suppression of cellular immunity may play an important role in reactivation of CMV in pregnancy.