Cell-mediated immune responsiveness to measles. Its occurrence as a result of naturally acquired or vaccine-induced infection and in infants of immune mothers.

Studies of cell-mediated immunity (CMI) to measles were carried out in patients with natural measles infection, in recipients of live measles vaccine, and in umbilical cord blood specimens from infants of mothers who were seropositive for measles. Evidence of CMI to measles was found in 100% of patients with natural infection but in only 62% of vaccine recipients and, interestingly, in 40% of umbilical cord blood specimens. Eight of these infants were subsequently studied at 4 to 5 months of age, at which time evidence of measles CMI was still detectable in three. Sufficient stimulation of cell-mediated immune mechanisms may be a prerequisite for the development of life-long immunity to measles. The effect of congenitally acquired CMI to measles on the outcome of immunization or of exposure to natural measles during the first year of life remains to be determined.