Leonard J. Cole

Protection of Mice Against X-Irradiation by Spleen Homogenates Administered After Exposure.

Summary and Conclusions 1. The mortality of adult LAf1 mice, exposed to whole-body X-irradiation in doses of 650, 700 and 800 r, was either prevented or reduced mark-edly following a single intraperitoneal injection of spleen homogenate administered either one hour or as long as 45 hours after radiation exposure. The equivalent of 1 to 2 spleens was injected into each irradiated mouse. The protective factor was present in homogenates from spleens of young mice (1 to 3 weeks old), and to a smaller degree in homogenates of spleens from adult mice. 2. The post-irradiation protection afforded by spleen homogenate injection was reflected in minimized weight losses observed in the spleen-homogenate-treated mice as compared with the control animals. The data suggest a possible quantitative relationship between the amount of spleen substance injected and the degree of protection obtained.

Parental-F1 Hybrid Bone Marrow Chimeras: High Incidence of Donor-Type Lymphomas

Summary Adult LAF1 hybrid mice received a whole-body exposure to 500 R of X-rays, followed by a single intravenous injection of 4 × 106 normal, parental strain (A/He) bone marrow cells, which produced no overt graft-versus-host morbidity or mortality. On sacrifice, 2 years later, a striking increase in the incidence of malignant lymphoma (76%) over that of appropriate controls, was observed. Transplantation tests with cell suspensions prepared from these lymphomas revealed that they are of donor strain—rather than host—origin. The key point for lymphomagenesis here may be the persistent, tolerated histoincompatibility associated with the parental strain-F1 hybrid bone marrow cell chimerism, rather than immunosuppression by graft-versus-host reaction.

Leishmania enriettii: radiation effects and evaluation of radioattenuated organisms for vaccination.

Abstract The effects of gamma radiation and ultraviolet light on motility, morphology, reproduction, ability to transform from amastigote to promastigote, infectivity, and vaccine potential of Leishmania enriettii were studied. Over 800,000 roentgens (R) was necessary to immobilize immediately the organisms, whereas only 25,000 R rendered them noninfective and 50,000 R made amastigotes unable to transform to promastigotes. Increasing degrees of morphological abnormality were seen with increased radiation doses. Single, double, and triple vaccination with 25,000–100,000 R irradiated organisms had no protective value against L. enriettii.

Studies on the chemical nature of the radiation protection factor in mouse spleen. I. Enzymatic inactivation by deoxyribonuclease and trypsin.

In previous studies from this laboratory (1, 2) it was found that the ability of mouse spleen homogenates to afford protection against radiation death, when injected into otherwise lethally X-irradiated mice, is associated with the nuclei fraction. Isolation of the spleen nuclei with retention of protective activity in the fraction was accomplished by the use of a fortified sucrose-salt medium in which the subcellular fractions were obtained by differential centrifugation of the spleen homogenate. No protective effect was observed after injection of spleen mitochondria, microsome, or soluble supernatant fractions. Attempts to obtain active nucleic acid extracts from the nuclei fraction, employing the molar NaCl extraction procedure of Mirsky and Pollister (3), yielded negative results. It is recognized that the deoxypentosenucleic acids, in association or combination with protein, comprise the major chemical constituent of the cell nucleus. In view of experimental evidence in the literature (4, 5) indicating that treatment of deoxypentosenucleoprotein complexes with 1 M NaCl elicits profound alterations in their physiochemical properties (e.g., dissociation of protein-nucleic acid linkages, changes in viscosity), it was proposed (2) that the protective factor in mouse spleen may be a nucleoprotein. The experiments to be described here were designed to test the validity of this hypothesis and to obtain further data on the chemical nature of the factor. To this end, crystalline enzymes have been employed as specific analytical reagents in the present study. As is well known, most enzymes are characterized by a marked specificity of action toward their substrate and exhibit activity under physiological conditions; these properties make possible their use in vitro as analytical reagents and provide a unique means of investigating the chemical

Graft-versus-host reactions in nonirradiated mice, early suppression of jerne plaques and hemopoietic colony-forming units.

The effect of graft-versus-host (gvh) reactions was studied at the cellular level. It was found that splenic plaque-forming cells (pfc) and hemopoietic colony-forming units (efu) of nonirradiated adult F1 hybrid mice were inhibited following injection with parental strain lymph node cells (107). Suppression of pfc was evident 3–6 days after injection and there was only 1% of the control pfe level by 10 days. It was found that the donor lymph node cells did not contribute significantly to the remaining pfe response. Colony-forming units were depressed in the spleen by 12 clays or earlier if larger numbers of parental lymph node cells (4.7 × 107)were injected. Suppression of efu in the bone marrow was not noted during the 12-day interval studied. These results may be interpreted as evidence that pfe precursor cells and/or efu are primary targets of the gvh reaction, but other indirect mechanisms, which are discussed, are not necessarily excluded.

STUDIES ON SYNERGISTIC THYMUS--BONE MARROW CELL INTERACTIONS IN IMMUNOLOGICAL RESPONSES.

Summary and Conclusions 1. Marrow cells and thymus cells which had been exposed in vivo to SRBC antigen interact synergistically to produce hemolysin plaque-forming cells (Table II) (2). 2. The possibility of similar thymus-marrow cell interaction in producing cell mediated responses was tested in a variety of systems. 3. Synergistic interactions were not observed: (a) in the restoration of homograft reactivity of sublethally irradiated mice (Fig. 1); (b) in the production of graft-vs.-host responses as measured by splenomegaly (Figs. 3, 4, and 5) or of secondary disease (Table III) (cf. 4); and (c) in the restoration of the homograft response in sublethally irradiated, thymectomized recipients injected with marrow cells and with spleen cells from irradiated mice which had been injected previously with thymus cells and “weak” isoantigen (non-H-2). 4. A nonspecific stimulation of the homograft response occurred under conditions similar to 3c above but where the isoantigenic disparity was strong. 5. This nonspecific stimulation and the resuits of Globerson (9) which show a synergism between thymus and marrow cells in the production of in vitro GVH responses, offer perhaps the only known evidence that thymus–marrow cell interactions are involved in cell-mediated immunological responses. 6. Specific syngergistic interactions so evident in the initiation of the hemolysin response do not occur when cell-mediated immunological responses are tested under similar conditions. This does not definitely rule out the possibility that thymus–marrow cell interactions are involved in cell-mediated immunological responses. 7. Under certain conditions, thymus and bone marrow cell populations, like lymph node cell populations are each capable of conferring cell-mediated immunological competence. Hence these cell populations may have either one cell type capable of responding to isoantigen, or two or more cell types which interact to produce the response.

Chronic Histoincompatibility and Lymphomagetosis in Mice

There is a growing body of knowledge suggesting that immunological factors may play a critical role in the induction of neoplasms. Apart from the evidence that immunosuppression per se may permit the growth and development of autochthonous tumor cells bearing neoantigens, it is possible that lymphoproliferative diseases such as malignant lymphomas may be the consequence of chronic, persistent histoincompatibility reactions involving immunocompetent cells, in a host animal which for one of several causes may, in effect, be an isoantigenic mosaic or chimera. Such a possibility derives not only from certain theoretical formulations by Burnet (l), Tyler (2), Dameshek and Schwartz (3), and Kaplan and Smithers (4), but also from earlier observations in two different types of experiments: the incidence of lymphomas in mouse radiation bone marrow chimeras from our laboratory (5), and the work of Schwartz and Beldotti (6) and of Walford and Hildeman (T), on the occurrence in popxilations of mice subjected to graft-versus-host reactions.