Tissue dynamics of CD8 lymphocytes that suppress viral replication in cats infected neonatally with feline immunodeficiency virus

The purpose of this study was to determine the tissue distribution and antiviral activity of the CD8 lymphocytes that suppress the replication of feline immunodeficiency virus (FIV). Cell-associated FIV load, CD8 alpha (+)beta (low) cells, and CD8 cell-mediated suppression of FIV were measured serially in the blood, thymus, and peripheral lymph nodes after neonatal inoculation. Between 6 and 10 weeks, relative numbers of CD8 alpha (+)beta (low) cells increased, whereas CD8 alpha (+)beta (high) cells declined in the thymus and blood of infected cats. By 12-16 weeks, the lymph nodes were enlarged because of an absolute expansion of all CD8 subpopulations. The strength of CD8 cell-mediated FIV suppression in vitro, but not CD8 alpha (+)beta (low) cell content, was correlated inversely with virus load in the thymus and blood. Thus, after neonatal FIV inoculation, CD8 alpha (+)beta (low) cells first occupy the thymus and blood, where strong CD8 cell-mediated antiviral activity is linked to reduced virus load in multiple lymphoid tissues.