DISTRIBUTION OF SIV IN LYMPH-NODES OF SERIALLY SACRIFICED RHESUS-MONKEYS

Rhesus monkeys were inoculated with SIVDeltaB670 and sacrificed 2, 4, 8, and 24 weeks after inoculation or when moribund. Two monkeys predic ted to have a rapid disease course and two predicted to have a Slower disease course were sacrificed at each time point. Lymph nodes were st udied by histopathology, immunohistochemistry, in situ hybridization, electron microscopy, flow cytometry for lymphocyte subsets, and mitoge n responsiveness. A greater selective decrease in peripheral CD4(+)CD2 9(+) (helper-inducer/memory) T cells occurred in monkeys with high ant igenemia. Although the percentage of CD8(+) lymphocytes was increased and the CD4(+)/CD8(+) ratio decreased in all infected groups, there we re no consistent differences between monkeys with high or low antigene mia in lymph node lymphocyte subsets. Blastogenic responses of lymph n ode lymphocytes to PHA, ConA, or PWM were not significantly altered in infected monkeys, A reticular pattern typical of antigen deposition w ithin germinal center follicular dendritic cells was seen in three mon keys with atrophic lymph nodes, high serum antigenemia, and a low perc entage of circulating CD4(+)/CD29(+) cells. More individually stained cells were in monkeys with high serum antigen and in moribund animals. By in situ hybridization, most monkeys had signal in a reticular patt ern of germinal centers. Animals with higher levels of serum antigenem ia tended to have more infected cells and a more intense signal. Extra cellular virions were found between the FDC foot processes in the germ inal centers of lymph nodes. Disease course was already established 2 weeks after inoculation.