Interferon production by and leukocyte phenotyping of rhesus monkey lymph node and peripheral blood cells

The ability of peripheral blood leukocytes to produce interferon-gamma (IFN-gamma) and be labeled with monoclonal antibodies against cell-surface markers was determined in this study. Both peripheral blood leukocytes and lymph node cells were able to produce IFN-gamma after challenge with mitogens. The rhesus monkey IFN-gamma was detectable by means of a biological assay but not by means of a radioimmunoassay for human IFN-gamma. Peripheral blood leukocytes and lymph node cells from rhesus monkeys (Macaca mulatta) were treated with fluoresceinated antibodies directed primarily against cell-surface antigens of humans. The degree of binding was determined by means of flow cytometry. Several of the anti-human antibodies did bind to the rhesus monkey peripheral blood leukocytes, as expected. In a novel study, the antibodies bound in a similar fashion to rhesus monkey lymph node cells. Binding of the antibodies was equivalent whether the cells came from inguinal or axillary lymph nodes. Rhesus monkey peripheral blood leukocytes incubated with recombinant human IFN-gamma showed enhanced expression of class II major histocompatibility complex antigens, as detected with anti-HLA-DR antibodies.