Evidence for selective proliferation and histological localisation of B lymphocytes in the human tonsil

Characterization of a polyclonal antibody to human thymidylate synthase suitable for the study of colorectal cancer specimens

Measurement of thymidylate synthase (hTS) using immunohistochemical techniques has been reported in several clinical studies. However, its value as a prognostic indicator is still not clear. To pursue this, we have developed a new rabbit polyclonal antibody, hTS7.4. The antigen was recombinant hTS containing an N-terminal His(6)-tag. Antiserum hTS7.4 detected recombinant hTS by ELISA at a titer of 1:100,000. Western blot analysis of several human cell lines showed a single band of the expected 36-kD molecular size. HeLa cells treated with the TS inhibitor 5-FUdR showed the expected additional band corresponding to the ternary complex of hTS-dFUMP-reduced folate. hTS7.4 detected TS in bacterial, rat, mouse, and monkey cell extracts, and hTS8.3 (a closely related antiserum) immunoprecipitated a 36-kD [(35)S]-methionine-labeled protein from HeLa extracts. TS was detectable by indirect immunofluorescence in HeLa cells. Proliferating normal human fibroblasts in culture showed staining, but nonproliferating cells did not. Lymphocytes in the germinal center of human tonsil tissue, which are known to be proliferating, stained with hTS7.4 and also with monoclonal antibody TS106. TS may therefore be useful as an immunohistochemical marker of cell proliferation. Normal colon mucosa showed weak staining, whereas some colorectal cancer specimens stained very strongly with hTS7.4. A clinical study of colorectal cancer using this antibody is in progress. (J Histochem Cytochem 47:1563-1573, 1999)

The emigration of lymphocytes from palatine tonsils after local labelling

Lymphocytes in the palatine tonsils of normal young pigs were selectively labelled by minute multiple injections of fluorescein isothiocyanate into the tonsils. One day later the numbers of tonsil-derived lymphocytes were determined in cervical, bronchial and mesenteric lymph nodes, spleen, Peyer's patches, thymus, bone marrow and blood. Although not all tonsillar lymphocytes could be labelled by this technique, a total of approximately 0.6 X 10(9) lymphocytes emigrated from the tonsils. Relatively more lymphocytes were found in lymph nodes than in the spleen and very few in the thymus, Peyer's patches and bone marrow. This organ distribution was different from the results from selectively labelling lymphocytes in lymph nodes, spleen and bone marrow.

Cell-size distribution of human tonsillar lymphocytes

Cell-size distributions of human tonsillar lymphocytes (TL) and adenoid lymphocytes (AL) were determined using a computerized cell-size analyser. In comparison with peripheral blood lymphocytes, TL, and AL comprised a greater number of large lymphocytes. Child TL were characterized by an enrichment of not only B-lymphocytes but also of large lymphocytes. A decrease in the number of large B-lymphocytes with advancing age was considered to be indicative of the morphological profile of tonsillar involution.

Theoretical and clinical aspects of the tonsillar function

A general review of the state of the art in tonsillar function research is given. A proliferation of B lymphocytes, evoked by antigens and/or polyclonal activators, occurs in the tonsil. Such a process, i.e. the supply of B cells to the organism facilitating a number of immune reactions, is to be considered the main function of the tonsil. The formation of antibodies must be regarded as a by-effect caused by an intratonsillar defence mechanism; it is helpful in safeguarding the structural and functional integrity of the organ. A model of the tonsil on the basis of cybernetics is derived from the results obtained and from the histological structure of the organ. Tonsillar involution is characterized by a decline in B cell proliferation, eventually leading to a weakening of the intratonsillar defence mechanism. Genetic disposition and defective functioning of the intratonsillar defence mechanism are discussed as pathogenetic factors in tonsillitis.

Factors of tonsillar involution: age-dependent changes in B-cell activation and Langerhans' cell density

Incorporation of radioactive thymidine as well as morphological and autoradiographical investigations performed with isolated B and T lymphocytes of the tonsil show that first of all B cells are activated or proliferating. The combination of autoradiography with cytochemistry was the only means of detecting a few activated T cells. With increasing age the number of activated B cells decreases. A reduced number of Langerhans' cells acting as antigen receptors in the epithelium of the crypt is assumed to be one cause of this phenomenon. Tonsillar involution originates from both a decline in the antigen receptors and in the depletion of B-cell activation. Malfunctions in these processes give rises to pathogenic factors in chronic tonsillitis.