Localization of T-lymphocyte areas in human lymphoid tissues by fluorochrome-labelled Helix pomatia A haemagglutinin.

Fluorochrome-labelled Helix pomatia A haemagglutinin (HP) stained T-dependent areas in cryostat tissue sections of human lymph node, tonsil, and spleen and thymocytes within thymic medulla but not within thymic cortex. Neuraminidase treatment of the tissue section was a prerequisite for the positive cell staining. The staining was cell-membrane-associated, and the histological pattern was essentially the same as that observed in parallel sections treated with monoclonal antibodies to T cells (OKT3, Leu-1). In addition, blood vessel walls and connective tissue were also stained by HP conjugates. The latter staining was independent of neuraminidase treatment, resistant to alpha-galactosidase treatment and was not blocked by pretreatment with anti-fibronectin antibody. Body types of staining reaction were specific inasmuch as unlabelled HP and the competitive sugar hapten N-acetyl-D-galactosamine blocked the reaction, Frozen, formalin-fixed tissue sections showed the same stainability and reaction pattern as unfixed sections.