Studies on Immune Defence Mechanism in Human Cytomegalovirus Infection. I. The Role of Local Humoral Immune Response in Human Cytomegalovirus Infection

Local secretory immune mechanism in infants with cytomegalovirus (CMV) infection was studied by a mesurment of neutralizing antibodies in saliva. The subjects consisted of infants with various diseases who were brought to the Out-patient Clinic or were admitted to the Pediatric ward of Sapporo Medical College Hospital during a period for July 1974 to May 1976. Neutralizing antibodies were determined by microplaque assay method in 65 saliva specimens; 54 samples from seropositive and 11 from seronegative subjects. In addition CMV isolation and antibodies determination in serum and saliva were simultaneuosly performed on 8 patients with CMV infection for longperiods. Results obtained were as follows ; 1. Neutralizing antibodies were detectable in 41 of 54 (76%) saliva specimens obtained from seropositive subjects but in none of 11 samples from sronegative subjects. The mean of 60% plaque reduction titer was2.8(2.8上). 2. Neutralizing antibodies in saliva were of low titer, but persistently detectable in all but one of the 8 patients. No relation was recognized between the cessation of virus excretion and the development of neutralizing antibodies in saliva. 3. Virus-neutralizing activity was specifically found in IgA fraction of pooled saliva by DEAE cellulose chromatography. 4. Thus secretory IgA antibodies were proved to be produced in salivary gland with CMV infection. The question remains, however, as to whether secretory IgA antibody functions protectivly in local infections with CMV