An experimental system for the simultaneous estimation of mitostatic and lymphotoxic effects of immunosuppressants and cytostatics

Sublethally (600 R) irradiated (CBA x C57BL)F(1) mice were grafted intravenously with parental lymph node cells in doses ranging from 0.2 x 10(6) to 12 x 10(6). The transplantation of these lymphoid cells leads to inactivation of the recipient's endogenous CFU (as measured by the diminution of the number of colonies registered on the 10th day after irradiation). A 50% inactivation was observed when the graft size of the CBA cells was 0.52 x 10(6). This figure for C57BL cells was 10 times more. This experimental system evaluates two simultaneously developing processes: the multiplication of endogenous CFU and the homograft reaction of transplanted lymphocytes against them. Both processes can be quantitatively estimated simultaneously in the same experiment by the determination of the number of colonies in corresponding experimental groups. Thus it was possible in a single experiment to compare quantitatively the effect of immunosuppressants on two points: (a) mitostatic action (suppression of CFU) and (b) lymphotoxic action. The latter, a true immunosuppressive effect, represents suppression of GVH activity of lymphoid cells and is demonstrated by abolition of the inhibition of endogenous colony formation. In the present system we have tested 6-MP, ALS, cyclophosphamide, hydrocortisone, and other drugs. The definite mitostatic and lymphotoxic doses of drugs are ascertained. Cyclophosphamide and ALS proved to be drugs with high dose ranges of selective lymphotoxic action. Hydrocortisone acetate had a more narrow range of selective lymphotoxic effect. 6-MP and Imuran (azathioprine) failed to exert any selective action on lymphoid elements. They possessed pronounced mitostatic efficiency, however.

Some observations on the acute histopathologic effects of cycloheximide in vivo

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Effects of cyclophosphamide on the ultrastructure of Peyer's patches

An electron microscope study has been made of the Peyer's patches of mice at intervals of between 6 hr and 30 days following a single sublethal injection of cyclophosphamide. Evidence of cellular damage and death was already present in some lymphocytes of the Peyer's patch at 6 hr. An early morphological change was the margination of dense chromatin at the nuclear membrane, with a rather sharp inner border. By 12 hr, large numbers of dead cells were present in the lymphoid tissue, either lying free or within the cytoplasm of macrophages. At 24 hr most of the dead cells and cellular remains were seen to lie within the cytoplasm of macrophages and the lymphoid tissue appeared less cellular than that of the controls. Apparently normal lymphocytes, plasma cells, eosinophils and reticular cells were still present, as well as large binucleate cells which were not seen in the controls. At later intervals, the profiles of the macrophage inclusions appeared smaller. By the 9th day, there was an apparent increase in the cellularity of the lymphoid tissue, and immature forms and cells in mitosis were seen more frequently. By the 18th day, the morphology of the Peyer's patch was indistinguishable from normal.

Studies on antilymphocyte antibody in the chicken. II. Effect of rabbit antithymus and antibursa globulin on immune reactions in young chickens

Four-week-old chickens repeatedly injected intraperitoneally with heterologous antithymus globulin (ATG) and antibursa globulin (ABG) were immunized, in the course of treatment, with bovine γ-globulin (BGG). The ATG and ABG depressed the production of anti-BGG antibody. On the other hand, only ATG was effective in suppressing experimental allergic encephalomyelitis. Immunoelectrophoretic analysis of sera from chickens treated with ATG, ABG and NRG (normal rabbit globulin) revealed that those globulins are themselves immunogenic. ATG and ABG induced in the spleen a moderate depletion of lymphocytes and plasma cells respectively. These reagents produced lymphocytopenia and granulocytopenia, but a similar, although less expressed, effect on leucocytes in the peripheral blood could be induced by NRG. Thymus, bursa, caecal tonsil, Peyer's patches and lymphoid masses of the intestine were not influenced by ATG, ABG and NRG. The results are discussed and interpreted as further evidence for the delineation between immune functions of the thymus and the bursa of Fabricius in the chicken.

Effect of mouse submandibular gland extracts on survival of H-2 incompatible skin allografts

Crude saline extracts of male mouse submandibular glands prolonged graft survival time in CBA and Strong A strains of mice, both when used alone and when used in conjunction with antithymocytic serum. It is suggested that this effect is produced by a lymphoid tissue inhibitory substance found in male mouse submandibular glands.

Changes produced by pertussis antigen on the blood cells and lympho-haemapoietic tissues after early and late thymectomy or splenectomy

The effect of thymectomy and splenectomy in C3H/Bi mice on the responses of circulating leucocytes and on morphological changes of the haematopoietic tissues after injection of pertussis vaccine has been studied.

After pertussis all mice showed depletion of lymphoid cells in all the lymphoid organs as well as in bone-marrow and an increased number of leucocytes, lymphocytes, neutrophils and monocytes in the circulation. Neonatal thymectomy decreased lymphocytosis produced by pertussis. Thymectomy, at all ages studied, fostered an increase in the number of monocytes and polymorphonuclears in circulation. Splenectomy at birth or early in life provoked an increase in levels of circulating polymorphonuclears and lymphocytes in pertussis treated animals.

In neonatally thymectomized mice the depletion of lymphoid cells from lymphoid tissues after pertussis could be shown to include the thymic-independent areas. The depletion of small lymphocytes from thymus following pertussis persisted longer than depletion of small lymphocytes from spleen, marrow or lymph nodes. The longer persistence of lymphoid depletion in the thymus than in peripheral lymphoid tissues is, we believe, to be related to the central lymphoid function of thymus as a site of differentiation of lymphoid cells and to the aloofness of thymus from recirculation of fully differentiated peripheral lymphocytes.

Effect of cortisone acetate on 19S and 7S haemolysin antibody. A time course study

A single subcutaneous injectio of cortisone acetate (400–500 mg/kg body weight) depressed the serum haemolysin response of adult Swiss mice to sheep erythrocytes when administered near the time of antigen injection. The greatest suppression of the early haemolysin response occurred when cortisone was injected 3–4 days prior to antigen, while the late antibody response (20–30 days after antigen injection) was markedly decreased when cortisone was given up to 4 days after antigen. Cortisone depressed both 19S and 7S haemolysin when given prior to antigen, but depressed only the 7S antibody when administered after antigen. An attempt was made to correlate the depression of the immune response with the decrease in lymphoid tissue following cortisone treatment and a striking correlation was observed between the number of circulating lymphocytes at the time of antigen injection and the 7 day titres of total and 19S antibody.

Antigen-induced changes in lymphoid cell histones. IV. Changes in solubility of isolated chromatin

In this study we have examined the solubility of deoxyribonucleoprotein (DNP) isolated from control and antigen-affected thymocytes. 2-M sodium chloride extracts containing the DNP of rat thymus glands were serially diluted. A comparison was made of the effect of dilution on fiber formation in the control and test series. Fiber formation is usually complete for the control material at a salt concentration between 0.63 and 0.57 M. The test material shows some fiber formation within this range. However, a significant portion of the DNP is precipitated at dilutions of 0.54-0.48 M. Ammoniacal silver (A-S) stains the control fibers a characteristic yellowish color. With the test material, those fibers formed within the control range tended to be stained yellowish brown by A-S, whereas those formed only after greater dilution stained blackish. These data, coupled with our previous observations on altered A-S staining, clearly demonstrate an antigen-induced physical and/or chemical alteration of the histone or histone-DNA complex of lymphoid cell chromatin.

Antigen-induced changes in lymphoid cell histones. 3. In vitro and in extract

Previous papers in this series have reported an acute, transitory effect of antigens on lymphoid cell nuclei. In the previous reports the effect was related to a change in ammoniacal silver (A-S) stainability of smears and cryostat sections. The variable substrate was identified as histone. This paper reports the results of an extended series of studies of histone and chromatin extracts from thymus glands exposed to antigen in vivo and in vitro. The antigen effect on A-S stainability is demonstrable not only in vitro but also in chromatin fibers representing a DNA-histone complex. However, it is not demonstrable in isolated histone fractions. The inference is drawn that the antigen-induced alteration in A-S stainability is brought about not by any quantitative change in histone, but by a biologically significant shift in histone binding, perhaps to DNA. It is suggested that alteration in DNA-histone binding during gene activation may alter A-S stainability of histones.