Assessment of the Parameters of Adaptive Cell-Mediated Immunity in Naïve Common Marmosets (Callithrix jacchus)

Common marmosets are small New World primates that have been increasingly used in biomedical research. This report presents efficient protocols for assessment of the parameters of adaptive cell-mediated immunity in common marmosets, including the major subpopulations of lymphocytes and main markers of T- and B-cell maturation and activation using flow cytometry with a multicolor panel of fluorescently labelled antibodies. Blood samples from eight common marmosets were stained with fluorescently labeled monoclonal antibodies against their population markers (CD45, CD3, CD20, CD4, CD8) and lymphocyte maturation and activation markers (CD69, CD62L, CD45RO, CD107a and CD27) and analyzed by flow cytometry. Within the CD45⁺ population, 22.7±5.5% cells were CD3- CD20⁺ and 67.6±6.3% were CD3⁺CD20-. The CD3⁺ subpopulation included 55.7±5.5% CD3⁺CD4⁺CD8- and 34.3±3.7% CD3⁺CD4-CD8⁺ cells. Activation and maturation markers were expressed in the following lymphocyte proportions: CD62L on 54.0±10.7% of CD3⁺CD4⁺ cells and 74.4±12.1% of CD3⁺CD8⁺ cells; CD69 on 2.7±1.2% of CD3⁺CD4⁺ cells and 1.2±0.5% of CD3⁺CD8⁺ cells; CD45RO on 1.6±0.6% of CD3⁺CD4⁺ cells and 1.8±0.7% of CD3⁺CD8⁺ cells; CD107a on 0.7±0.5% of CD3⁺CD4⁺ cells and 0.5±0.3% of CD3⁺CD8⁺ cells; CD27 on 94.6±2.1% of CD3⁺ cells and 8.9±3.9% CD20⁺ cells. Female and male subjects differed in the percentage of CD3⁺CD4⁺CD45RO⁺ cells (1.9±0.5 in females vs 1.1±0.2 in males; p < 0.05). The percentage of CD20⁺CD27⁺ cells was found to highly correlate with animals' age (r = 0.923, p < 0.005). The basal parameters of adaptive cell-mediated immunity in naïve healthy marmosets without markers of systemic immune activation were obtained. These parameters and the described procedures are crucial in documenting the changes induced in common marmosets by prophylactic and therapeutic immune interventions.