FLOW CYTOMETRIC ANALYSIS OF B-CELL AND T-CELL SUBPOPULATIONS IN SPECIFIC-PATHOGEN-FREE CHICKENS INFECTED WITH INFECTIOUS BURSAL DISEASE VIRUS

Lymphocytes obtained from the blood, spleen, and bursa of normal chick ens and of chickens infected with infectious bursal disease virus (IBD V) were analyzed for phenotypic expression of CT4, CT8, and immunoglob ulin cell surface markers. Single-cell suspensions were stained with m onoclonal antibodies by an indirect immunofluorescent assay, and perce nt staining was quantitated by flow cytometry. Although an appreciable decline from control levels in the percentage of lymphocytes expressi ng IgM was detected in the spleen and bursa of infected chickens, the relative proportions of lymphocytes expressing CT4 and CT8 in peripher al blood and spleen remained unchanged following infection. These resu lts suggest that whereas humoral immune depression by IBDV may be asso ciated with lysis of antibody-producing B cells, cellular immune depre ssion is not associated with a detectable change in the proportion of helper or cytotoxic/suppressor subpopulations of T lymphocytes.