T. Himi et al., EFFECT OF RADIOTHERAPY ON THE LEVELS OF SECRETORY IMMUNOGLOBULIN-A AGAINST INDIGENOUS AND VIRULENT STREPTOCOCCI, Otolaryngology and head and neck surgery, 117(5), 1997, pp. 433-437
It is well known that the frequency of upper respiratory infection is
clinically increased after radiotherapy of the head and neck region. T
his study found higher antibacterial secretory immunoglobuin A (S-IgA)
activity against three indigenous streptococci (Streptococcus mitis,
S. salivarius, and S. sanguis I) and S. pneumoniae in patients who had
undergone radiation therapy of the head and neck region than in contr
ol subjects. This showed no relation to the extent of the radiation fi
eld. Compared with before radiotherapy the S-lgA titer against S. pneu
moniae and its ratio to the activities against the indigenous streptoc
occi were significantly higher in patients with fully irradiated major
salivary glands. These results indicated that the radiotherapy promot
ed the antigen-specific S-lgA production of virulent streptococci in m
ost patients with head and neck cancer, even more than 6 months after
radiotherapy. The resulting altered balance in the S-IgA system of nor
mal indigenous streptococci may also impair the ability to maintain th
e stable bacterial interference between normal indigenous and virulent
streptococci in the oropharyngeal cavity.