BCG vaccination induces enhanced frequencies of dendritic cells and altered plasma levels of type I and type III interferons in elderly individuals

Kumar, Nathella Pavan; Padmapriyadarsini, Chandrasekaran; Rajamanickam, Anuradha; Bhavani, Perumal Kannabiran; Nancy, Arul; Jayadeepa, Bharathi; Selvaraj, Nandhini; Ashokan, Dinesh; Renji, Rachel Mariam; Venkataramani, Vijayalakshmi; Tripathy, Srikanth; Babu, Subash

OBJECTIVE: : BCG can improve the response to vaccines directed against viral infections and also BCG vaccination reduces all-cause mortality, most likely by protection against unrelated infections. However, the effect of BCG vaccination on the dendritic cells (DC) subsets is not well characterized. METHODS: : We investigated the impact of BCG vaccination on the frequencies of DC subsets and type I and III interferons (IFNs) using whole blood and plasma samples in a group of elderly individuals (age 60-80 years) at one month post vaccination as part of our clinical study to examine the effect of BCG on COVID-19. RESULTS: : Our results demonstrate that BCG vaccination induced enhanced frequencies of plasmacytoid DC (pDC) and myeloid DC (mDC). BCG vaccination also induced diminished plasma levels of type I IFNs like IFNα and IFNβ but increased levels of type III IFNs IL-28A and IL-29. CONCLUSIONS: : Thus, BCG vaccination was associated with enhanced DC subsets as well IL-29 in elderly individuals, suggesting its ability to induce non-specific innate immune responses.