CD8A and major depressive disorder: Participants (N = 526) completed quantitative assessments of self-reported incarceration history, behavioral (e.g., antiretroviral therapy (ART) adherence, stimulant use) and psychosocial factors (e.g., depression, perceived stress), and provided biospecimens to assess immune function (i.e., CD4:CD8 ratio) and quantification of plasma HIV viral load.