Efficient in vivo depletion of CD8+ T lymphocytes in common marmosets by novel CD8 monoclonal antibody administration

•Peripheral CD8+ T lymphocytes of common marmosets were efficiently depleted in the blood by administration of the marmoset CD8-specific monoclonal antibody.•The CD8 depletion in marmosets persists for at least three weeks or longer.•This is the first report in New World monkeys showing the establishment of new methodology to be capable of depleting common marmoset CD8+ T lymphocytes in vivo.

In order to directly demonstrate the roles of CD8+ T lymphocytes in non-human primates, in vivo depletion of the CD8+ T cells by administration of a CD8-specific monoclonal antibody (mAb) is one of the crucial techniques. Recently, the common marmoset (Callithrix jacchus), which is classified as a New World monkey, has been shown useful as an experimental animal model for various human diseases such as multiple sclerosis, Parkinson's disease and a number of infectious diseases. Here we show that an anti-marmoset CD8 mAb 6F10, which we have recently established, efficiently depletes the marmoset CD8+ T lymphocytes in vivo, i.e., the administration of 6F10 induces drastic and specific reduction in the ratio of the CD8+ T cell subset for at least three weeks or longer. Our finding will help understand the pivotal role of CD8+ T cells in vivo in the control of human diseases.