Binding of peanut lectin to thymic cortex and germinal centres of lymphoid tissue.

The binding pattern of horseradish peroxidase conjugated peanut lectin (HRP-PNL) on frozen sections of lymphoid tissue from man, mouse, rat, hamster, guinea-pig, rabbit, sheep and chicken has been investigated. Binding of PNL was found to be highly species dependent; man, mouse and sheep showed strong binding to lymphocytes in thymic cortex and germinal centres; lymphoid tissue from hamster, guinea-pig and rabbit did not stain with HRP-PNL and rat showed only lightly positive cells in thymic cortex and germinal centres; all lymphoid tissue from chicken, except the bursal cortex, bound PNL. Neuraminidase treatment of tissues which did not bind PNL resulted in strongly PNL-positive cells. Double binding studies on murine Peyer's patches with fluorescein isothiocyanate conjugated PNL (FITC-PNL) and tetramethylrhodamine isothiocyanate (TRITC)-anti-Thy-1.2 or anti-immunoglobulin reagents revealed 3%-10% of PNL positive cells to be Thy-1.2 positive and 70%-80% to bear surface immunoglobulin.