AUTHOR=Kostinov Mikhail Petrovich , Akhmatova Nelli Kimovna , Karpocheva Svetlana Victorovna , Vlasenko Anna Egorovna , Polishchuk Valentina Borisovna , Kostinov Anton Mikhailovich 

TITLE=Vaccination Against Diphtheria and Tetanus as a Way to Activate Adaptive Immunity in Children with Solid Tumors

JOURNAL=Frontiers in Immunology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.696816

DOI=10.3389/fimmu.2021.696816

ISSN=1664-3224

ABSTRACT=Early studies on vaccination of children with oncological diseases were dedicated to nothing but assessment of safety and immunogenicity of the drug. Mechanisms of the post-vaccination immune response were not investigated.
The study involved 41 patients aged 7-15 years treated against solid tumors two or more years ago. Of these, 26 were vaccinated against diphtheria and tetanus with ADS-m toxoid. 15 children (i.e., controls) were not vaccinated. The vaccination tolerability and clinical characteristics of the underlying disease remission ware assessed. Lymphocyte subpopulations were investigated over time by flow cytometry in 1-6-12 months. IgG anti-diphtheria and anti-tetanus toxoids levels were assessed by ELISA. 
Within the first day of the post-vaccination period, 2 (7.7%) children demonstrated moderate local reactions and increased body temperature (up to 38.0 ºС). Relapse and metastasis were not mentioned within a year after immunization. An increase in concentration of IgG antibodies, maintained for 12 months, were noted (2.1 [1.3-3.4] IU/ml against diphtheria (p <0.001), 6.4 [2.3-9.7] IU/ml against tetanus (p <0.001)). In contrast to healthy children, those with a history of cancer demonstrated a decrease in relative number of mature T-lymphocytes, as well as in absolute number of cytotoxic T-cells and B-lymphocytes. In a month after the revaccination, a significant increase in absolute (p = 0.04) and relative (p = 0.007) numbers of T-lymphocytes and T-helpers was revealed. In a year these values decreased to baseline levels. As for helpers, they decreased below baseline and control values (p = 0.004). In a year after the vaccination there was a significant (p = 0.05) increase in lymphocyte level with a decrease in number of NK cells and B cells as compared with controls.  
Revaccination against diphtheria and tetanus promoted proliferation of total lymphocytic cell pool along with restoration of T-lymphocyte subpopulation in children with a history of solid tumors. ADS-m toxoid has a certain nonspecific immunomodulatory effect. These findings are important, also in the midst of the coronavirus pandemic.