[Immunodepressive action and effects of medroxyprogesterone acetate on the lymphatic tissue of the rabbit appendix]

The influence of medroxyprogesterone acetate (MPA) on lymphoid tissue of rabbit appendix was investigated. The agent caused a uniform depletion of lymphoid cells, which confirmed the immunodepressive properties of the drug. Other findings suggested a corticoid action of the agent and a possible anticellular activity, interfering with nucleic acid synthesis of proliferating cells.

[Lymphoid tissue of the human vermiform appendix and its cellular composition at different ages]

The lymphoid tissue of 55 human appendices has been studied beginning from 25 weeks of the intrauterine development up to 80 years of age. Most of lymphocytes have been found to include immunoglobulines of various types; in some cases alcaline phosphatase activity was evident in lymphocytes of the mantle zone of lymphatic follicles in children and grown-up persons, and lack of acidic phosphatase activity in lymphocytes make it possible to consider the appendicular lymphoid tissue as a B-dependent type of lymphoid tissue. A suggestion is made that during the intrauterine development and the early childhood the appendicular lymphocytes could settle in other lymphoid formations.

[Immunosuppressive action and effects of amethopterin on the lymphoid tissue of the rabbit appendix]

Effects of amethopterin (MTX) on lymphoid tissue of rabbit appendix have been evaluated. The drug caused an evident depletion of lymphoid cells. This finding suggested the relevance of cytotoxicity in the mechanism of immune suppression. Discontinuation of drug treatment demonstrated a tendency toward the reorganization of the lymphoid tissue.

Antigenicity restoration of formaldehyde-treated material with chymotrypsin

In histological preparations commonly fixed in formaldehyde and embedded in paraffin which on immunofluorescent examination yielded results negative results or but very poor immunofluorescence, prominently positive results were obtained by chymotrypsin treatment on using the method of fluorescent antibodies. Corresponding results were also obtained in cryostat sections fixed for some min up to several days in formaldehyde so that immunofluorescence was completely negative. The positive immunofluorescent results indicate total or partial restoration of antigenicity of tissue proteins previously altered by formaldehyde.

[Immunomorphologic study of experimental enteric anc combined vaccination against cholera]

As a result of the enteral and combined subcutaneous-enteral immunization of adult rabbits with cholerogen toxoid and the specific fraction of chemical cholera vaccine in tablets immunological transformation occurred in the organism and a "protective" barrier consisting of antibody-containing cells was formed in the intestine on days 3-5. The combined method of immunization with cholera vaccine proved to be essentially as effective as enteral immunization in 2 administrations.

[Immunological aspects of inflammatory bowel diseases (author's transl)]

The gastrointestinal tract is replete with immunocompetent tissue represented by appendix, Peyer's patches and nonaggregated lymphocytes in the intestinal epithelium. This local immune system plays a vital role in the physiologic immune response and in the control of food, drug, microbial or viral antigens. Under certain situations this lymphoid tissue may contribute to the immunological reactions underlying the pathogenesis of various diseases. Generalised deficiencies of the immune apparatus frequently give rise to disturbances of gastrointestinal function. Furthermore plenty of immune reactions occurring in connection with human inflammatory bowel disease have been described. Some immunologic features are reported as typical for a disease, the majority seems to indicate only nonspecific autoimmune reactions. The relevance of immunological mechanisms for the pathogenesis of these diseases is still not full evaluated.

Immunohistochemical analysis of formaldehyde- and trypsin- or pepsin-treated material

Immunohistochemical studies of paraffin sections of formaldehyde-fixed material and formaldehyde-fixed cryostat sections treated with trypsin or other enzymes were undertaken. Formaldehyde treatment resulted mostly in partial or total loss of antigenicity, as visualized by fluorescent antibody technique in tissue sections. The digestion of sections with trypsin resulted usually in total or partial restitution of antigenicity, previously altered with formaldehyde. This effect is suggested to consist primarily in breaking formaldehyde-induced intermolecular cross-links. Restitution of antigenicity altered by formaldehyde can also be achieved on using pepsin or other proteolytic enzymes, or by some other technique. When the effect of one enzyme proves insufficient, it can readily be complemented by the action of another enzyme applied subsequently. Mild trypsin treatment preserves well the morphological structure of most tissues.

Responsiveness of rabbit spleen and appendix cells to bacterial mitogens

Rabbit spleen and appendix cells were used to test the mitogenic activity of a commercial lipopolysaccharide (LPS) preparation from Salmonella typhimurium (Difco), a preparation extracted from it, and cell wall preparations from smooth (45/0) and rough (45/20) strains of Brucella abortus. On the basis of [3H]thymidine incorporation ratios (E/C), that is, the incorporation rate among cells treated with the mitogen relative to that of untreated cells, the extracted LPS and both Brucella cell wall preparations, but not the commercial LPS were potent mitogens for rabbit spleen cells. By the same criterion, only the Brucella cell wall preparation produced a significant, but minimally so, response among appendix cells. The weak responsiveness of appendix cells may be more apparent than real, however, and may not imply a difference in intrinsic susceptibility to mitogens by these two populations, because unstimulated appendix cells incorporated thymidine at 10 times the rate of unstimulated spleen cells. Appendix cells, then, may not be susceptible to further stimulation, even by active mitogens. Therefore, the significance of E/C ratios may be equivocal when materials are assayed for mitogenic activity on lymphoid populations whose basal activity is relatively high.

T- and B-cell surface markers on rabbit lymphocytes

Rabbit thymus, appendix, blood and lymph nodes were characterized using immunological tests: rosette-forming ability with homologous or heterologous red blood cells, surface immunoglobulins, analytical cell-electrophoresis, cell refringency and in vitro mitogen responsiveness. The experiments were conducted on normal rabbits and cyclophosphamide-treated rabbits. Moreover, we tried to separate slow and high mobility cells by free-flow electrophoresis into fractions. These experiments suggest that rabbit lymphocyte behaviour is exceptional among mammals in that the majority of their lymphocytes appeared as B cells and that, in comparison with mouse and man, the proportions of these cells are inversed.

Complement receptor lymphocytes in the rabbit I. an SIg-negative subpopulation in the appendix

Complement receptor lymphocytes (CRL) were detected in various rabbit lymphoid tissues by the ability of these CRL to form rosettes with sheep red blood cells coated sequentially with rabbit antiserum directed against sheep red blood cell stroma and horse serum as a nonhemolytic source of complement (EAC). The rosette assay was shown to be specific for complement receptor (CR) activity and the EAC capable of detecting both C3b and C3d specific receptors. With lymphocyte preparations containing less than 5% phagocytic cells, the average per cent CRL in the various tissues studied was as follows: thymus 1%, popliteal lymph node 18%, spleen 30%, appendix 35%, and peripheral blood 45%. Double assays in which the lymphocytes were prestained with an FITC-labeled Fab fragment of a goat anti-rabbit Fab antibody before rosetting indicated that CRL were a subpopulation of surface immunoglobulin (SIg)-bearing lymphocytes in popliteal lymph node, spleen, and peripheral blood. In the appendix, however, in addition to finding SIg+ CR+ and SIg+ CR- populations, an SIg- CR+ population was consistently found. Double assays employing FITC-labeled goat antibodies specific for mu, alpha, and gamma determinants were also performed to determine if there was any relationship between the class of Ig displayed and presence of CR. It appeared that an approximately equivalent percentage of both IgM- and IgG-bearing cells also displayed CR. Experiments in which appendix cells were treated with Pronase to remove SIg and CR and the cells cultured in vitro to allow regeneration of surface markers confirmed the existence of SIg+CR+, SIg+CR-, and SIg-CR+ lymphocyte subpopulations. Whether the SIg-CR+, population represents a developing B cell population which will eventually also express SIg or whether it belongs to the T or "null" cell populations is unclear at present.

Localization of T and B lymphocytes in human adenoid, tonsil, appendix and Peyer's patches

T and B lymphocytes were detected in human adenoid, tonsil, appendix and Peyer's patches by adherence to sheep erythrocytes (E) and human erythrocytes sensitized with antibody and complement (HEAC). The percentages of T lymphocytes in adenoid and tonsil cell suspensions averaged 30.9 +/- 3.4 (S.D.) and 35.8 +/- 6.4 (S.D.). The percentages of B lymphocytes in the same tissues were 42.5 +/- 11.3 (S.D.) and 40.1 +/- 34 (S.D.) respectively. In adenoid and tonsil tissue sections, B lymphocytes were found in the follicles and T lymphocytes were detected around the follicular areas. The predominant cell population in Peyer's patches and appendix sections was constituted by B lymphocytes.

Rationale of incidental appendectomy

In an effort to settle the controversy regarding use of incidental appendectomy, we have reviewed the literature regarding the function of the appendix and its role in the development of cancer, incidence of acute appendicitis, pathologic findings in incidentally removed appendices, and morbidity of incidental appendectomy. Considering all parameters we conclude that incidental appendectomy is a service to the patient and should be done except where specifically contraindicated.

[Histochemical characteristics of the secretory elements of the vermiform appendix following surgical trauma, circulatory hypoxia and immunization]

Histochemical methods were applied to determination of salomycin, dermatansulfate, keratosulfate and neutral mucopolysaccharides in the goblet cells of rabbit appendix. Sialomycin and neutral mucopolysaccharides were found in the glands. Immunization with human gamma globulin was followed in the productive phase of immunogenesis by a rise of the secretory activity of the mucosa of the appendix. An increase of the mucus formation in the appendix occurred after laparatomy and during the initial period of experimental appendicitis. However, surgical trauma caused an opposite effect against the background of increased functional activity of the secretory elements of the immunized animals, and during experimental appendicitis no activation of mucus formation was seen. The influence of the abovementioned factors on the secretory activity of the mucous membrane was accompanied by qualitative changes in the synthesized mucus.

B and T cells in lymphoid tissues of human appendix

Human appendix lymphoid cells (HAL) react very strongly to stimulation with concanavalin A, strongly to stimulation with phytohaemagglutinin, and weakly but definitely to stimulation with lipopolysaccharide. From the results of rosette formation assay, cytotoxicity tests with anti-T cell antiserum or anti-B cell antiserum, cell surface or intracellular immunoglobulin staining with fluorescein-conjugated rabbit anti-Fab of human immunoglobulin serum, and plaque-forming cell (PFC) assay, it was concluded that human appendix lymphoid tissue is a B cell pool but includes T cells. However, both direct and indirect PFC could not be significantly demonstrated against sheep red blood cells in a 5-day HAL culture.

Increased proportion of B lymphocytes in human tonsils and appendices

The percentage of T and B lymphocytes was studied in human tonsils and appendices. An increased percentage of B lymphocytes, 59.1% in tonsils and 54.5% in appendices, was found, whilst the percentage of T lymphocytes was 23.6% and 27.9%, respectively. In the peripheral blood of the corresponding figures were 12.5% for B cells and 50% for T cells.

[Separation and immunological characterization of lymphocytes isolated from human appendix (author's transl)]

The isolation of viable lymphocytes from fresh human appendices is described. Under standardized experimental conditions of cell preparation no selective enrichment of either T- or B-lymphocytes was observed. The mean percentage of T-lymphocytes as judged by spontaneous rosette formation found in 34 appendices examined was 50.0%. After overnight incubation surface-Ig was detected by immunoradioautography on 46.8% of the recovered lymphocytes from 10 appendices. For the detection of surface-Ig specifically purified antibodies to heavy chains mu, gamma and alpha were used. Of the 46.8% surface-Ig positive lymphocytes the class distribution was as follows: IgM 17.7%, IgG 24.4% and IgA 4.7%. The isolated lymphocytes showed a variable mitotic response to PHA (stimulation index ranging from 3.3 to 200.9) as well as to allogeneic lymphocytes in a one-way mixed lymphocyte culture. So far, a distinct correlation could not be found between the histological degree of inflammation and the class or mitotic response of appendix lymphocytes.

B cells in the appendix and other lymphoid organs of the rabbit: complement receptor lymphocytes

Complement receptor lymphocytes were demonstrated in rabbit lymphoid organs, the spleen containing the highest numbers (35%) and the thymus none. Extremely variable numbers (up to 50%) were detectablein the appendix. B and T cell depletion, rosette depletion, and histologic staining indicate that these CRL are B cells in the rabbit as in other species. The variable behavior of B cells in the appendix suggests a difference between this lymphoid organs population and those of other rabbit lymphoid organs.

Cells involved in the immune response. XXVIII. the cellular composition of the lymphoid organs in the normal outbred rabbit

Horse anti-rabbit spleen cell antiserum was obtained by the intravenous immunization of horses with rabbit spleen cells. The antisera obtained were analysed for their lymphocytotoxic activity with respect to the lymphoid cells of the different lymphoid organs prior to and following absorption with the different lymphoid cells. The results have been integrated with those obtained in previous investigations and an all-embracing concept of the interrelationship of the lymphoid cells in the different lymphoid organs in the rabbit has emerged. The distinction between the heretofore considered central lymphoid organs (bone marrow and thymus) and peripheral lymphoid organs (spleen, lymph node and appendix) has been blurred by the finding that, at least in the rabbit, appendix cells possess specific antigen markers and participate in cell-mediated immune reactions in vitro and the observation that the spleen also has a central lymphoid function in the generation of cells in vivo capable of carrying out a cell-mediated immune reaction in vitro. It is concluded that the distinction of central and peripheral lymphoid function may be an artificial one in that it may reflect a function of the particular organ in only one of the many different types of immune reactions and that it should not influence the investigator in the elucidation of the cellular mechanisms participating in the mediation of the different immune responses.

[Palatine tonsils and immunity. IV. Lymphocyte blast transformation in various lymphoid organs of animals immunized with microbial antigens]

For the purpose of ascertaining the peculiarities of cellular differentiation of lymphoid cells of the palatine tonsils experiments were conducted on rabbits immunized intravenously and subcutaneously with streptococcus and paratyphoid B antigens; a study was made (in the blast-transformation reaction) of a comparative response of the lymphocytes of the palatine tonsils, the thymus, the spleen, the appendix and the regional lymph node. In case of stimulation with the specific microbial antigens and PHA the proliferative response was greater in the culture of the splenic lymphocytes and the regional lymph node than in the culture of the lymphocytes of the palatine tonsils and the appendix. The thymus lymphocytes responded to PHA only. A conclusion was drawn that the paratyphoid B and streptococcus antigens penetrating into the lymphoid tissue by hematogenic route stimulated a relatively low percentage of lymphocytes of the palatine tonsils and the appendix in comparison with the regional lymph node and the spleen.

[Reproduction of the anaphylactic reaction of isolated human smooth muscle organs and the effect of several adrenotropic substances]

A comparative study was carried out of passive sensitization of the lungs, bronchi, small and large intestine by the blood sera of patients sensitive to ambrosia pollen. Passive sensitization and subsequent anaphylactic contraction were reproduced on the isolated bronchi, lungs and the ileum. Development of this reaction was less constant in the large intestine, jejunum and the appendix. The value of anaphylactic reaction of human smooth muscle displayed significant changes with the treatment of the muscles by agents selectively acting on the beta-adrenergic receptors of these organs.

Subpopulations of thymus dependent and thymus independent lymphocytes in human gut associated lymphoid tissues

Human gut associated lymphoid tissues were studied in terms of the presence of subpopulations of thymus dependent and thymus independent lymphocytes. Both thymus dependent and thymus independent lymphocytes were present in substantial numbers, as judged from their ability to form spontaneous and complement mediated rosettes with sheep red blood cells and the presence of surface bound immunoglobulins. The relationship between this finding and the question of what is the lymphoid organ which may be the human equivalent of the avian bursa is discussed.

B-cell mitogenic effects on human lymphocytes of rabbit anti-human beta 2-microglobulin

Rabbit Ig against human beta2-microglobulin was found to be mitogenic for human peripheral lymphocytes, tonsil lymphocytes, and appendix and spleen cells. Anti-beta2-m gave increased DNA synthesis, with peak responses on day 3 or 4 and showed a dose-response effect when diluted. The effect was seen in both serum-free and serum-containing culture medium. Anti-beta2-m, as well as lipopolysaccharide, induced polyclonal antibody production and intracellular immunoglobulin synthesis in blast cells, which is taken as evidence that these substances are human B-cell mitogens. Anti-beta2-m, but not lipopolysaccharide, could, in these experiments, activate peripheral blood lymphocytes, in addition to lymphoid cells from other sources. Thus, anti-beta2-m can serve as a functional marker for peripheral human B lymphocytes.

Restriction of gene expression in B lymphocytes and their progeny. III. Endogenous IgA and IgM on the membranes of different plasma cell precursors

Fluorescent antibody staining with antibodies to the f and g locus allotype markers present on rabbit alpha-chains revealed that the alpha-chain is the heavy chain on the Peyer's patch lymphocytes which previously had been shown to be the precursors of IgA-producing plasma cells. In addition, lymphocytes which had been stripped of membrane Ig with pronase and then cultured overnight to allow the sole expression of endogenous membrane Ig were found to have either the micro-chain or the alpha-chain on their membranes, but not both. These results suggest that most lymphocytes are restricted to the synthesis of one class of heavy chains at a time and that the commitment to synthesizing that particular heavy chain is maintained during the differentiation of lymphocytes into plasma cells. The proportion of lymphocytes with membrane alpha-chains is higher in the Peyer's patch and appendix, two gut-associated lymphoid tissues (GALT), than in other lymphoid tissues. Since the GALT are enriched sources of precursors for IgA-producing plasma cells compared to nongut-associated tissues, the presence of cells bearing membrane alpha-chains correlates well with the relative abilities of these tissues to generate IgA plasma cells.

Cells involved in the immune response. XXVII. The demonstration of appendix-specific antigens in the rabbit

Rabbit appendix cells were injected into horses at weekly intervals, after which the horses were bled and the sera tested for cytotoxic activity. The unabsorbed antiserum was cytotoxic to the lymphocytes of all the lymphoid organs tested. Following absorption with bone marrow and thymus cells, the antiserum lost all cytotoxic activity directed toward these cells but displayed almost undiminished cytotoxic activity toward the cells of the SAPP organs (sacculus rotundus, appendix and Peyer's patches). The absorbed antiserum also demonstrated cytotoxic activity toward certain lymphocytes present in the spleen, lymph node and circulation. Thus, the antibodies directed toward the antigens common to all lymphoid cells were removed by the thymus and bone marrow cells, leaving behind cytotoxic antibodies directed toward antigens present on appendix and appendix-derived cells only. We have therefore succeeded in preparing antisera specific for rabbit thymus, bone marrow and appendix cells, respectively.

Plaque-forming cells in rabbits following stimulation of the appendix with sheep erythrocytes

Sheep erythrocyte (SRBC) antigen was delivered directly into the lymphoid component of the appendix or via the appendicular artery, followed by ligation or clamping of appendicular vessels. Antigen was also injected intravenously, into the spleen, or into the thymus. Counts of anti-SRBC plaque-forming cells (PFC) in the appendix were compared with counts in the spleen and thymus. None of the injection routes employed resulted in an elevation of PFC activity above background in the appendix. However, delivery of antigen via the appendicular artery caused a marked increase of PFC activity in the spleen. These results and other available evidence point towards a helper-cell function of lymphocytes in the appendix, and therefore suggest a central role of this organ in humoral immunity.

Germinal centres and the origin of the B-cell system. I. Germinal centres in the rabbit appendix

Regeneration of follicular structures in the rabbit spleen after a single dose of 450 rads whole body X-irradiation was shown to be dependent upon the presence of the appendix.

Results obtained were in favour of a stream of cells—probably derived from appendix germinal centres—to follicular structures in the spleen, in particular to the lymphocyte corona and marginal zone but excluding germinal centres.

Recovery of the antibody forming potential following X-irradiation was equally shown to be dependent upon the presence of the appendix.

It was concluded that following 450 rads whole body X-irradiation the appendix contributes to the recovery of the antibody forming capacity of the spleen by the production of antibody-forming cell precursors; these latter cells are presumably identical with the follicle replenishing class of lymphocytes derived from appendix germinal centres.

Allotype suppression in the rabbit. I. The ontogeny of cells bearing immunoglobulin of paternal allotype and the fate of these cells after treatment with antiallotype antisera

The ability to distinguish immunoglobulin (Ig) of paternal allotype both on lymphocyte membranes and in the serum of neonatal b(4)b(5) heterozygous rabbits has allowed us to study the postnatal ontogeny of cells bearing endogenously synthesized Ig that could not have been derived from the mother. In normal b(4)b(5) rabbits, such endogenously synthesized Ig of paternal allotype is present on the membranes of bone marrow-derived (B) lymphocytes from birth, but does not appear as detectable circulating Ig until approximately 2 wk of age. In the neonate, cells bearing the paternal allotype are potential targets for the induction of chronic allotype suppression. Within 24 h of exposure to anti-allotype antisera in vivo, Ig of the suppressed paternal allotype is no longer detectable on the surface of neonatal lymphoid cells. Further, this lymphocyte membrane Ig is eliminated and not simply masked by the suppressing antibodies. Finally, cells bearing the suppressed allotype are deleted from all lymphoid organs for the duration of total allotype suppression, and reappear first in bone marrow and peripheral blood at the time of spontaneous escape from suppression.