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The cytotoxicity of peripheral blood mononuclear cells (PBMC) to human arterial smooth muscle cells (SMC) infected with cytomegalovirus (CMV) or herpes simplex virus-1 (HSV) was investigated. PBMC were isolated from heparinized blood of healthy donors by Ficoll-Hypaque centrifugation and were tested for cytotoxicity against human SMC or human fibroblast-like (MRC-5) cells infected with CMV or HSV, using the chromium-51 (51Cr) release cytotoxicity assay. Both SMC and MRC-5 cells infected with either CMV (SMC-CMV), (MRC-5-CMV), or HSV (SMC-HSV), (MRC-5-HSV) were lysed by PBMC above background lysis of uninfected SMC cells. Treatment of PBMC with NK-specific monoclonal CD16 antibody and rabbit complement reduced greatly the lysis of SMC, SMC-CMV, and K562 cells, suggesting that lysis of different types of target cell by PBMC was mediated mainly by natural killer (NK) cells. The pattern of natural cytotoxicity against SMC-CMV was different from that against SMC-HSV. Maximum lysis of SMC-CMV was observed at 24 hr postinfection compared to 8 hr postinfection for SMC-HSV. NK reactivity against SMC-CMV increased from 8 to 24 hr postinfection, followed by a gradual decline at 48 and 72 hr. Supernatants generated by culturing SMC-CMV or coculturing SMC-CMV with PBMC enhanced NK cell-mediated lysis of SMC or SMC-CMV. Natural cytotoxic reactivities of PBMC against SMC-CMV or SMC-HSV may occur in vivo. Such reactions could moderate the interaction of these viruses with vascular SMC and could influence the development and/or the progression of atherosclerotic lesions.

Amphotropic and ecotropic packaging cell lines were used to obtain high titers (greater than 10(6) colony forming units/ml) of retroviruses encoding human argininosuccinate synthetase, and these viruses were used to transduce murine bone marrow cells using cocultivation in vitro. The bone marrow cells were transplanted into lethally irradiated recipient mice, and argininosuccinate synthetase activity was measured in peripheral blood. Transduction with amphotropic retrovirus resulted in short-term expression for a period of 1-8 weeks, and no animals expressed the human gene after 25 weeks. Over 60% of the animals transplanted with cells transduced with ecotropic retrovirus expressed the human gene 44 weeks post-transplant, although the level of expression varied over a wide range. Analysis of the DNA from transplanted animals demonstrated the presence of the human sequence in expressing animals, and S1 nuclease analysis of RNA confirmed the presence of the human RNA transcripts. Analysis of granulocyte/macrophage (GM) colonies derived from the bone marrow of transplanted, expressing animals revealed a correlation between the level of expression of the transduced gene with the percentage of GM colonies carrying the human gene sequence. These data demonstrate the feasibility of obtaining long-term expression of genes introduced into bone marrow cells using retroviral vectors and the feasibility of obtaining expression of a gene not normally expressed in bone marrow.

The distribution and localization of adenosine deaminase (ADA) was studied during postnatal development of the alimentary tract in mice. There was detectable enzyme activity in all organs examined, but a range of more than 10,000 fold in the relative levels of specific activity was observed among adult tissues. A comprehensive survey of multiple adult tissues revealed that the highest levels of ADA occur in the upper alimentary tract (tongue, esophagus, forestomach, proximal small intestine). Immunohistochemical analysis revealed that ADA was predominantly localized to the epithelial lining of the alimentary mucosa: the keratinized squamous epithelium that lines the forestomach, esophagus, and surface of the tongue; and the simple columnar epithelium of the proximal small intestine (duodenum, proximal jejunum). Biochemical analysis revealed that ADA was one of the most abundant proteins of these mucosal tissue layers, accounting for 5%–20% of the total soluble protein. Tissue-specific differences in ADA activity correlated both with levels of immunoreactive protein and RNA abundance. The level of ADA activity in the upper alimentary tissues was subject to pronounced developmental control, being low at birth and achieving very high levels within the first few weeks of postnatal life. The appearance in development of ADA-immunoreactivity coincided with maturation of the mucosal epithelium. These results suggest that ADA is subject to strong cell-specific developmental regulation during functional differentiation of certain foregut derivatives in mice.

To test the hypothesis that genetic susceptibility or resistance to diet-induced atherosclerosis is correlated with serum levels of specific lipids, lipoproteins, or apoproteins, male mice of a genetically susceptible and a genetically resistant strain were fed either a normal or an atherogenic diet. After 20 weeks on a normal diet, neither the resistant nor the susceptible strain mice had atherosclerosis; resistant strain mice had serum cholesterol of 66 +/- 11 while the susceptible strain mice had 90 +/- 1 mg/dl serum cholesterol, and lipoproteins were dominated by a single alpha-migrating HDL. After 20 weeks on an atherogenic diet, resistant strain mice had 185 +/- 55 mg/dl cholesterol, their lipoproteins remained dominated by alpha-migrating HDL, and two of eight mice had mild atherosclerotic lesions; susceptible strain mice had 510 +/- 94 mg/dl cholesterol, multiple alpha- and pre-beta-migrating lipoprotein species, and all 13 had advanced aortic atherosclerosis. The resistant strain mice had an apolipoprotein E/total lipoprotein protein ratio of 0.42 on the normal diet and 0.53 on the atherogenic diet, while the susceptible strain mice had the significantly lower ratios of 0.07 and 0.31, respectively. These data indicate that genetic resistance to diet-induced aortic atherosclerosis in mice is correlated with capacity to prevent large increases in serum cholesterol, to suppress abnormal alpha- and pre-beta-migrating lipoproteins, and to maintain elevated serum apolipoprotein E/total lipoprotein protein ratios. Our data do not preclude the possibility of additional gene control at the level of arterial end organ response.

Lymphoid cells from normal inbred LSH and random-bred Syrian golden hamsters were evaluated for natural cytotoxic activity against cultured simian adenovirus 7 (SAT)-induced lymphoma of the LSH hamster employing the 51Cr-release cytotoxlcity assay. Natural cytotoxic reactivity was found in both inbred and random-bred hamsters. The level of activity was much higher in random-bred (38.2% lysis) than in inbred (14.9%) hamsters. The percentage lysis of SA7 target cells was proportional to the effector:target cell (E:T) ratio. Natural cytotoxic reactivity was high in both spleen and bone marrow intermediate in mesenteric lymph node, and low or non-existent in thymus. Natural cytotoxic responses were present In 4-to 7-day-old, adult and aged (1-to 11/2-year-old) hamsters. Exposure of hamsters to 1,100 R of whole-body irradiation had little or no effect on natural cytotoxic reactivity, indicating the radio-resistant nature of the reactivity in hamsters, as in mice. Treatment of hamsters with a single dose of either 500 mg cytoxan/kg intraperitoneally (IP), or 5 mg carrageenan IP markedly suppressed their natural cytotoxic responses, as in mice. Growth of transplanted SA7 tumor in inbred hamsters or of D., lymphoma in random-bred hamsters strongly inhibited the natural spleen-cell-mediated lysis of SA7 lymphoma cells. Thus, while hamster natural cytotoxic activity shared most of the properties of mouse NK activity, it differed in (1) appearing earlier in life (2) increasing progressively into older age (1 1/2 years) and (3) being as high in bone marrow as in spleen, or higher.

Bone marrow from barrier-sustained specific pathogen-free (SPF) CBA and C57BL/6 mice gave relatively low numbers of BFU-E colonies in methylcellulose culture, as compared to conventional mice. Addition of thymocytes to the marrow cultures increased the yield of BFU-E colonies more than fourfold in SPF mice but only 1.5-fold in conventional mice. Colony size was also increased. Increased yield of BFU-E colonies was also obtained by co-culture of bone marrow with lymph node cells or with bone marrow or spleen cells from 900R whole-body irradiated mice. The effect appeared to be cellular rather than humoral. It was not reproduced by conditioned medium from thymus or pokeweed mitogen stimulated spleen cells. The helper effect of thymus cells was eliminated or reduced by freezing and thawing, or by 48 hours of incubation after irradiation. Treatment of bone marrow cells in vitro with anti-theta serum and complement did not decrease the number of BFU-E colonies. The putative helper cells appear not to be T cells, were non-adherent to the plastic culture dish, and were cortisone resistant and radioresistant. The low BFU-E colony yield from SPF mouse marrow is presumed to be largely the result of deficiency of these non-T helper cells in SPF bone marrow, rather than of BFU-E progenitor cells.

Two transplantable hepatic carcinomas of the hamster contained CELO virus-induced TSTA, confirming the etiological role of this avian adenovirus in the induction of hepatic tumors. Transplantation resistnace could not be induced with oncogenic adenoviruses of human, simian, or canine origin.

The B95-8 cell line, a widely used source of highly transforming Epstein-Barr virus (EBV), obtained from the laboratory of origin, harbored an infectious retrovirus. This retrovirus generally resembled the Type D retroviruses structurally and developmentally and like the Type D retroviruses preferred Mg2+ to Mn2+ in its RNA-directed DNA polymerase reaction. Evidence for the presence of retrovirus was found in B95-8 cultures from two other sources within the United States, either by assay for polymerase or by electron microscopy. Comparison of two B95-8 cell lines showed cytogenetic differences as well as differences in retroviral activities. The results suggest that any B95-8 culture should be tested for the presence of retrovirus before its use as a source of EBV.

The effect of neonatal thymectomy on the development of splenic and bone marrow natural cell-mediated cytotoxicity and on genetic resistance to bone marrow transplantation was examined in mice. Natural cytotoxicity was measured by a 51Cr release assay; the ability to engraft foreign bone marrow was assayed by the spleen colony method. The natural cytolytic response of spleen cells increased progressively from youth to early adulthood, whereas that of the bone marrow declined during the same age period. Neonatal thymectomy significantly elevated the natural killer cell response of young mice only (4 weeks, spleen; 6 weeks, bone marrow). In other experiments, neonatally thymectomized and sham-operated mice were lethally irradiated at 4 or 6 weeks of age and injected with 2.5, 5.0 or 10 million rat marrow cells. Six days later spleen colonies were markedly reduced in both 4- and 6-week-old neonatally thymectomized mice with all rat marrow cell doses tested. Neonatal thymectomy did not alter the percentage of erythroid versus other colonies at either 4 or 6 weeks. In both thymectomized and sham-operated mice the number of colonies increased with increases in marrow cell dose. The data are suggestive of a production and dissemination to the spleen of cells involved in the natural cytotoxic response from the bone marrow.

51Cr-labeled parental strain spleen cells were pretreated in vitro with antithymocyte globulin (ATG) or Fab fragments of ATG before i.v. injection into F1 recipients. Recipients were killed at various intervals after injection and their organs were assayed for radioactivity in order to determine the in vivo distribution pattern of pretreated cells. 51Cr spleen cells pretreated with ATG were almost totally prevented from migrating to spleens, lymph nodes, bone marrow, Peyer's patches, lungs, and peripheral blood of recipients. Pretreatment of 51Cr spleen cells with noncytotoxic Fab of ATG also inhibited localization to these organs and tissues; however, the inhibition was not as complete as that of ATG-treated cells. Localization of Fab-treated 51Cr spleen cells to recipient nodes was inhibited to a greater extent than was localization to recipient spleens. There was no significant difference in the extent of inhibition of ATG-treated 51Cr spleen cells to recipient nodes and spleen. Organ counts from recipients killed at various intervals after injection of Fab-treated 51Cr spleen cells showed that Fab-treated cells do not recover their recirculating potential in vivo.

Adult mice were given a single sublethal dose of cyclophosphamide. Effects of the drug on the bone marrow-derived (B) and thymus-derived (T) cell compartments were measured by studies on lymphocyte transformation, lymphoid tissue morphology and responsiveness to a primary injection of keyhole limpet hemocyanin. These studies indicated that the effect of cyclophosphamide on the B cell compartment was more severe and longer-lasting than the effect on the T cell compartment.

Adult mice were made tolerant to equine γ globulin (EqGG) and to equine-anti-mouse-thymocyte globulin (ATG) by injection of EqGG (deaggregated, heat-aggregated, or in Freund's adjuvant) or ATG followed by cyclophosphamide (CY). Injection of deaggregated EqGG alone resulted in only “marginal” tolerance, whereas the other injections alone were immunogenic. The resulting tolerance could be shown to be of long duration without further antigen or drug injections. Relationships between the dose of CY required for tolerance induction and the timing of the drug in relation to antigen administration were established.

Spleen colonies produced by sublethally irradiated mouse bone marrow cells were compared to those produced by unirradiated marrow cells in lethally irradiated mice. Sublethally irradiated marrow cells gave rise to many fewer spleen colonies. At seven days of colony age, the ratio of erythroid colonies to granuloid colonies was lower (< 1) than for colonies formed by unirradiated marrow (2 to 3 or more). Delay of harvest of colonies to day 10 or 12 resulted in 6 to 11 fold increase in the ratio of erythroid to granuloid colonies due largely to the belated appearance of erythroid colonies.

Increased rates of plasma clearance of 125I-labeled horse IgG were observed in 16 of 17 patients treated with a prolonged course of anti-lymphocytic globulin (ALG) and in 3 of 5 volunteers who received a single small dose of ALG. Rapid immune elimination of ALG developed within 2 weeks of starting ALG treatment, and was accompanied by (1) the development of circulating anti-horse IgG antibodies which could be measured by passive hemagglutination or immunoadsorbent assays and by (2) the return of established delayed hypersensitivity which initially had been suppressed by the ALG treatment. Radioactively labeled horse IgG was found in the 7S region of sera of four patients tested before development of rapid immune elimination. In three patients studied after onset of rapid immune elimination of horse IgG, the serum proteinbound radioactivity sedimented more rapidly than 7S in the ultracentrifuge. In one case, the labeled protein was completely removed from the circulation within minutes of injection and broken down into small molecular weight fragments. Absorption of ALG after intramuscular injection was impaired in the presence of anti-horse IgG antibodies. These results suggest (1) that antibodies form in allograft recipients against ALG despite simultaneous treatment with large doses of azathioprine and corticosteroids, and (2) that these antibodies interfere with the absorption, distribution and the immunosuppressive effectiveness of ALG.

Lymphoid cell lines from Americans with infectious mononucleosis (Choate, EH IV, and OP), and from a normal American (Cassio), were tested for presence of herpes-like virus by electron microscopy (EM) and immunofluorescence (IF), and for complement-fixing (CF) antigens, using both American and African sera. Whereas earlier tests of seven African (Burkitt) lymphoma cell lines showed an absolute correlation between presence of herpes-like virus and CF reactivity with either African or American sera, the same was not true of the American cell lines. Herpes-like particles were found in the Cassio line by both EM and IF, and in a few cells of the OP line by IF, but not by EM. The virus was not found in the Choate or EH IV lines by either EM or IF. African sera from either normal individuals or patients with Burkitt lymphoma contained CF antibodies to extracts of Cassio and OP cells. Normal American sera contained CF antibodies to these extracts as well as to extracts of Choate cells. The EH IV cell line did not produce CF antigens detectable with either African or American sera. The data indicate that the CF antigens of the herpes virus-negative Choate cell line were serologically distinct from those in Burkitt lines. However, it is possible that the antigens from both sources are related to the presence of the genome of the herpes-like virus.

The human heart is highly vulnerable to rejection. In 16 patients with 17 allografts rejection progressed relentlessly in histocompatibility matches of C and D grades. Only three patients were still living, 63 to 181 days after transplantation, at the time of this report. The longest survival was 203 days. Signs of rejection were an increase in congestive heart failure, pericardial friction rub, electrocardiographic changes, malaise and a rise in the serum lactate dehydrogenase-1 level. Immunosuppression with azathioprine, adrenal steroids and antilymphocytic globulin has not been as successful in combating rejection over the long term as earlier experience indicated.

The sequential development of the CELO-specific T and virion antigens was studied in lytically infected chick kidney cells using the indirect immunofluorescence technique. The T antigen was detected 6 hours after infection, and rapidly increased until a peak was reached at 20–24 h. The V antigen could not be detected until 20 h after infection. The V antigen, but not the T antigen, was inhibited by cytosine arabinoside. Both antigens were inhibited by cycloheximide. After storage in liquid nitrogen for 3 weeks, the T antigen in fixed cells could not be detected by indirect immunofluorescence tests. Le Developpement des Antlgfines V et T du Virus Celo Dans les Cellules Renales de Poulet Lytiquement Infectees Le diveloppement siquentiel des antigines V (virioniques) et T speicifiques du virus CELO ete par immunofluorescence indirecte sur les cellules renales de poulets lytiquement infectkes. L'antiment T a eete dicelk 6 heures apres infection et a rapidement prolifere jusqu'a ce qu'un maximum soit atteint entre la vingtisme et favingt-quatrieme heure. l'antigene V n'est apparu que 20 heures apres l'infection. Contrairement a l'antigene T, l'antigene V a ete inhibe par la cytosine arabinoside. Les deux antigenes out ete inhibes par le cycloheximide. Les tests d'immunofluorescence indirecte n'ont pas permis de deceler d'antigene T dans les cellules fixees conservees pendant trois semaines dans de l'azote liquide.

SummaryHepatomas were induced in approximately 4% of inbred LSH/LAK hamsters inoculated subcutaneously with CELO virus. The sera from these animals stained the CELO T antigen found in lytically infected chick kidney cells. The tumors contained hamster types A and C virus particles. The relationship between these indigenous hamster viruses and tumor induction by CELO virus is being investigated.

Publisher Summary This chapter discusses the transfer of natural killer (NK) activity and lymphoma resistance to AKR mice by marrow from high NK, lymphoma-resistant (C57×AKR)F 1 mice. In the study described in the chapter, AKR mice, aged 4 to 6 weeks, received 950 R whole-body irradiation ( 137 Cs) followed by intravenous transfusion with 10 7 marrow cells from either the AKR strain, or the high NK, low-spontaneous-leukemia (C57×AKR)F 1 hybrid, or the low NK, high-spontaneous-leukemia (C3H×AKR)F 1 hybrid. Age-matched untreated control and chimeric AKR mice were tested at 2 to 4 week intervals for spleen cell mediated cytolysis of YAC-1 lymphoma cells by 4 h chromium release assay. From 2 to 12 weeks post-irradiation and marrow transfusion, spleen cell mediated lysis was higher in AKR mice rendered chimeric with marrow from the high NK-reactive, low leukemia (C57×AKR)F 1 strain than from the low NK reactive, high-leukemia (C3H×AKR)F 1 or AKR strains, and higher than age control untreated AKR mice.

Eleven avian adenovirus strains were tested for the presence of avian adeno-associated viruses (AAAV). Six strains contained AAAV. Electron microscopy using rabbit anti-AAAV serum was useful in detecting the satellite virus. The AAAV previously isolated from guail bronchitis virus was related to each of the six new isolates by immunoagglutination, complement fixation, immunodiffusion, and neutralization tests.

One and one-half percent of human sera from patients seen at a clinic for treatment of cancer contained antibodies to the nuclei of chick kidney cells by indirect immunofluorescence tests. In the group of sera containing antinuclear antibodies, the geometric mean titer to Epstein-Barr virus (EBV) capsid antigen was significantly elevated. Sera obtained from normal adults or from patients with similar histological types of tumors that possessed no antinuclear antibodies contained lower levels of anti-EBV antibodies. The elevated titers to EBV were correlated with the presence or absence of antinuclear antibodies and not with a particular type or site of neoplastic disease.

Hamsters immunized with either noninfectious hamster type-C virus (D9) or irradiated D9 tumor cells were tested for cell-mediated immune reactivity by the macrophage migration inhibition assay. The migration of peritoneal exudate cells from immunized hamsters was significantly inhibited by either D9 virus or D9 tumor extract, but not by extract of an unrelated CELO virus-induced tumor. The virus and tumor extracts had little or no effect on the migration of peritoneal exudate cells from normal hamsters. Noninfectious D9 virus produces a cell-mediated immune response in the hamster and shares antigenicity with D9 lymphoma, which releases the virus.

The first demonstration of the oncogenicity of a human virus was the induction of malignant transplantable tumors by injection of human adenovirus Type 12 into newborn hamsters (1), or mice (2). Tumors arose early at any of several sites of injection, and sometimes remotely, usually in the liver, resulting in death from tumor growth in from 29 to 108 days (3). The tumors were histologically undifferentiated malignant neoplasms (4). They contained virus-induced transplantation antigens (5) and newborn hamsters could be passively protected against tumor induction by immunization of the mothers before pregnancy (6).

We have examined the reported role of suppressor cells in the regulation of NK activity in mice with naturally low NK activity (infant and aged (C57 X A)F1 hybrids (CAF1) and low responder strain AKR mice). Possible suppressor activity was assayed by mixing, at a 1 : 1 ratio, spleen cells from low activity mice with spleen effector cells from normally active 8 to 10 wk old CAF1 mice. The lytic activity of the mixture was compared with the activity of effector cells diluted with medium alone or diluted 1 : 1 with "non-suppressor" population which served as a control for nonspecific decreases in lysis. The control or "filler" cells employed were suspensions of adult CAF1 thymus, thymus from adult mice exposed to 2,000 R, and adult CAF1 spleen cells cultured for 24 hours, a procedure that depleted NK activity. In no case was the activity observed in the presumed suppressor-effector mixture significantly lower than that observed in the filler-effector cell mixtures. Thus, in infant (1 to 2 wk) and aged (12 to 18 mo) CAF1 mice and in 8 to 10 wk old AKR mice, we found no evidence for specific cell-mediated suppression of natural cytotoxicity.

As part of an effort to develop a model system for somatic gene therapy, a human argininosuccinate synthetase (AS) cDNA has been introduced into two gag+ retroviral vectors, and high titer clones were obtained for both constructs. The presence of proviral DNA sequences was detected in individual spleen colonies after infection of primary murine marrow cells with each virus. Mice were reconstituted for long-term survival with marrow infected with one virus, and they demonstrated elevated levels of AS expression in peripheral blood for up to eight weeks posttransplantation.

We have previously reported the protective effect of pretreatment of semiallogeneic marrow and spleen cells with Fab fragments of horse anti-mouse thymocyte globulin against otherwise 100% fatal acute graft-versus-host disease (GVHD). We have now examined the effect of this pretreatment in three allogeneic strain combinations of mice, namely, A leads to C57, CBA leads to CAF1, and CBA leads to BALB/c. Acute GVHD mortality at 15 days postirradiation and transplantation of untreated marrow and spleen cells was 100% in all the strain combinations. However, pretreatment of cells with Fab reduced acute GVHD mortality to 6, 13, and 33% for the CBA leads to CAF1, CBA leads to BALB/c, and A leads to C57 strain combinations, respectively. The combined mortality from both acute and secondary GVHD and all other causes at 60 and 200 days postirradiation was 6 and 11%, 20 and 39%, 50 and 66% for each of these strain combinations, respectively. These results provide additional evidence for the effectiveness of Fab in ameliorating acute GVHD and establish its applicability to allogeneic strain combinations.

Publisher Summary This chapter examines the possible role of natural killer (NK) cells in radiation leukemogenesis. The study described in the chapter investigated the effect of fractionated irradiation of C57BL/6 mice, with or without marrow transfusion, on NK cell activity and development of thymic lymphoma. Over a period of many months, C57BL/6 mice reared in the barrier sustained cesarean derived, SPF mouse colony, aged 4 to 6 weeks, half of each sex, were randomized into unirradiated age control groups and irradiated groups. The latter received 4 weekly exposures to 225R 137Cs. Four to seven hours after the last exposure, half of the irradiated mice received 107 C57 bone marrow cells intravenously. Marrow-transfused, nontransfused and age-control mice were tested at intervals thereafter for spleen natural cell-mediated lysis of YAC-1 lymphoma target cells, by a 4 hour chromium release method, with or without 1 or 5 days prior intraperitoneal injection of the interferon inducers Poly l:C (PIC) or Coryne bacterium parvum (CP), respectively. Spleen NK cell activity was depressed by fractionated irradiation. Bone marrow transfusion after the last irradiation significantly increased NK cell activity by 1 week post transfusion, to essentially normal levels throughout the 8 weeks post transfusion.

Publisher Summary This chapter examines the peripheral blood natural cell-mediated cytotoxicity in patients with atopic dermatitis. Natural cell-mediated cytotoxic activity of the peripheral blood lymphocytes was studied in 10 patients with atopic dermatitis, and simultaneously in a healthy control matching each patient for sex, skin, color, and age ± 6 years. Eight patients gave a family history of allergic disease (as atopic dermatitis, asthma, hives or allergic rhinitis), and four patients had a personal history of asthma. None of the patients had systemic corticosteroids for at least a year prior to the investigation, and none had anti-histamines for at least 48 h before blood samples were obtained. Mononuclear leucocytes were separated using LSM solution. K562 target cells were maintained in RPMI containing 20% inactivated FCS, were radio-labeled by incubation with 51Cr as sodium chromate at 37°C for one hour, centrifuged, washed, and adjusted to a count of 0.2 × 106 viable cells/ml. The results showed that there was a marked reduction in the natural cytotoxicity of most of the atopic dermatitis patients studied. The patients with the least or no reduction in natural cytotoxicity were the three with only moderate or mild degrees of atopic dermatitis.

Malignant neoplasms in general acquire neo-antigens, usually called tumor-specific transplantation antigen (TSTA). Chemically induced tumors usually exhibit antigens unique to each tumor, whereas tumors induced by a virus share a common antigen specific for that virus regardless of the histological type of tumor or host species in which the tumor was induced (1–3). These TSTA invoke an immune response, mainly of cell-mediated type. The immune control or progressive growth of the tumor depends upon many factors including strength of the cellular immune response (degree of sensitization of lymphoid cells), “sneaking through” or appearance of serum blocking factor (1, 3–5), and suppressor cells (6–8). It has generally been accepted that thymus-dependent lymphocytes (T) are primarily responsible for rejection of tumors (9–15). There is considerable evidence that macrophages also contribute an important effector mechanism against tumors (16). Recently, natural killer (NK) cells are also thought to be involved in tumor surveillance (17–19). Most of the studies of effector mechanisms of tumor immunity have been carried out in vitro, using various cytotoxicity assays. To assess the role of in vivo cell-mediated immune responses in tumor immunity, two main approaches usually have been used. One consisted of studying the influence of immuno-suppression (x-irradiation, thymectomy, anti-lymphocyte serum) on the development of tumors (20–24). The alternate approach is to augment cellular immune responses either through non-specific stimulation such as Bacillus Calmette-Guerin (BCG), Corynebacterium parvum (CP), poly I:C, etc. (25–28), or through adoptive transfer of specifically sensitized lymphoid cells (29–31).

Using six mouse strain combinations, we attempted to prolong cardiac allograft survival by pretreatment of recipients with a single iv injection of donor-specific whole blood or spleen cells plus a single ip injection of cyclophosphamide (Cy). Significant prolongation of cardiac allograft survival occurred in a small proportion of pretreated mice of some strain combinations, with some grafts surviving for periods longer than 6–9 months. Cy injected alone did not influence the normal cardiac allograft rejection time of between 1 and 2 weeks. Depending upon the strain combination, accelerated rejection of all or some of the grafts occurred in mice pretreated with blood or spleen cells or myocardial cells alone.

Natural killer (NK) cells have been reported in several species including mice, rats, hamsters, guinea pigs, miniature swine, chickens and humans (1–14). These normal unsensitized lymphocytes exhibit cytolytic activity against a variety of targets including tumors and virus-infected cells (15–18). NK cells that have been studied extensively in mice and humans are small, non-adherent, non-phagocytic lymphocytes that originate in the bone marrow (14,19–22). NK cells lack conventional levels of T- and B-cell surface markers. Human NK cells have readily detectable Fc receptors on their surface, whereas mouse NK cells may express only low concentrations of Fc receptor, which are difficult to demonstrate (23). Recently it has been shown that NK cells of both mice and humans may have a low level of T-cell markers such as theta antigen and E rosette receptors, respectively (24,25). NK-cell activity is age-related (1,2) and genetically controlled (26, 27).

Prior treatment of human allograft recipients with aggregate-free normal horse immunoglobulin circumvents the problem of antibody formation in subsequent anti-lymphocytic globulin therapy.

SummaryThe human mixed lymphocyte culture reaction (MLCR) as measured by incorporation of 14C-thymidine is inhibited in the presence of an appropriate concentration of equine anti-human lymphocyte globulin (ALG). Fab fragments prepared from ALG also inhibit the MLC reaction. However, unlike the intact ALG molecules, the Fab fragments are noncytotoxic for human lymphocytes. ALG derived Fab fragments could be potentially useful in suppressing allograft reactivity in vivo.We thank Dr. Gordon R. Dreesman for performing the analytical ultracentrifuge analyses and Mrs. Jane Ann Martin for her technical assistance.

SummaryThe in vitro response to phytohemagglutinin (PHA) and pokeweed mitogen (PWM) of lymphoid cells from thymectomized, irradiated, bone marrow reconstituted (TIR) mice was compared to that of intact age controls. TIR spleens, lacking cells of the thymus-dependent compartment, responded only to pokeweed mitogen, whereas spleens from intact donors responded to both PHA and PWM. These results suggest that PHA stimulates thymus-dependent cells; whereas PWM stimulates cells of the non-thymus-dependent compartment.

Hemopoietic spleen colonies arising in lethally irradiated mice repopulated with limited numbers of bone marrow cells have been shown to be clonal in origin (1,2), each arising from a single stem cell or colony forming unit (CFU).