Circulatory Lymphocytes Research Articles

Time-course of interleukin-10 in dogs with cutaneous wounds

Aim: The study explores the time-course of serum and wound fluids, interleukin (IL)-10 in dogs with cutaneous wounds and their relationship with some haematologic parameters. Methods: The study comprised two groups of adult apparently healthy male and female dogs. The control (n = 6) dogs were intact (wound free) while the experimental (n = 6) dogs had surgically induced cutaneous wounds on the mid-lateral aspect of the right antebrachium. Whole blood, harvested serum and wound fluids samples, pre- and sequentially over 324 hours post-surgery, were utilised for Leucogram evaluation and Interleukin (IL)-10 assay. Results: Levels ofIL-10 in the experimental groups was higher than the corresponding control levels. The Circulatory level of IL-10 (1.67 ± 0.33 ng/mL) was significantly (P < 0.001) higher than those in wound fluid (0.87 ± 0.03 ng/mL) and control serum (0.94 ± 0.17 ng/mL) at 156 h. Haematocrit and total Leucocyte counts remained within normal reference limits, with minimal changes in differential cellular activities of the experimental and control groups. Significant correlations of serum IL-10 with lymphocytes (r = 0.946; P < 0.05) was observed in injured dogs. Conclusion: These findings indicate that IL-10positively modulated the inflammatory processes following cutaneous wounds with variable but significant impacts on circulatory lymphocytes count. It provided evidence that further investigations into the expression patterns of IL-10 in cutaneous wound may improve the quality of wound management.

Immune profile of primary and recurrent epithelial ovarian cancer cases indicates immune suppression, a major cause of progression and relapse of ovarian cancer

BackgroundOvarian cancer is the third most prevalent cancer in Indian women. Relative frequency of High grade serous epithelial ovarian cancer (HGSOC) and its associated deaths are highest in India which suggests the importance of understanding their immune profiles for better treatment modality. Hence, the present study investigated the NK cell receptor expression, their cognate ligands, serum cytokines, and soluble ligands in primary and recurrent HGSOC patients. We have used multicolor flow cytometry for immunophenotyping of tumor infiltrated and circulatory lymphocytes. Procartaplex, and ELISA were used to measure soluble ligands and cytokines of HGSOC patients.ResultsAmong the enrolled 51 EOC patients, 33 were primary high grade serous epithelial ovarian cancer (pEOC) and 18 were recurrent epithelial ovarian cancer (rEOC) patients. Blood samples from 46 age matched healthy controls (HC) were used for comparative analysis. Results revealed, frequency of circulatory CD56Bright NK, CD56Dim NK, NKT-like, and T cells was reduced with activating receptors while alterations in immune subsets with inhibitory receptors were observed in both groups. Study also highlights differential immune profile of primary and recurrent ovarian cancer patients. We have found increased soluble MICA which might have acted as “decoy” molecule and could be a reason of decrease in NKG2D positive subsets in both groups of patients. Furthermore, elevated level of serum cytokines IL-2, IL-5, IL-6, IL-10, and TNF-α in ovarian cancer patients, might be associated with ovarian cancer progression. Profiling of tumor infiltrated immune cells revealed the reduced level of DNAM-1 positive NK and T cells in both groups than their circulatory counterpart, which might have led to decrease in NK cell’s ability of synapse formation.ConclusionsThe study brings out differential receptor expression profile on CD56BrightNK, CD56DimNK, NKT-like, and T cells, cytokines levels and soluble ligands which may be exploited to develop alternate therapeutic approaches for HGSOC patients. Further, few differences in the circulatory immune profiles between pEOC and rEOC cases, indicates the immune signature of pEOC undergoes some changes in circulation that might facilitated the disease relapse. They also maintains some common immune signatures such as reduced expression of NKG2D, high level of MICA as well as IL-6, IL10 and TNF-α, which indicates irreversible immune suppression of ovarian cancer patients. It is also emphasized that a restoration of cytokines level, NKG2D and DNAM-1on tumor infiltrated immune cells may be targeted to develop specific therapeutic approaches for high-grade serous epithelial ovarian cancer.

A panel of human neutralizing mAbs targeting SARS-CoV-2 spike at multiple epitopes

The novel highly transmissible human coronavirus SARS-CoV-2 is the causative agent of the COVID-19 pandemic. Thus far, there is no approved therapeutic drug specifically targeting this emerging virus. Here we report the isolation and characterization of a panel of human neutralizing monoclonal antibodies targeting the SARS-CoV-2 receptor binding domain (RBD). These antibodies were selected from a phage display library constructed using peripheral circulatory lymphocytes collected from patients at the acute phase of the disease. These neutralizing antibodies are shown to recognize distinct epitopes on the viral spike RBD. A subset of the antibodies exert their inhibitory activity by abrogating binding of the RBD to the human ACE2 receptor. The human monoclonal antibodies described here represent a promising basis for the design of efficient combined post-exposure therapy for SARS-CoV-2 infection.

Maria de Sousa, (1939-2020).

Maria de Sousa, (1939-2020).

Association of absolute lymphocyte count and circulating CD4+ and CD8+ t-cells with positive clinical outcome in survivors of cancer: An observational study

Background: The objective of this observational study is to determine the changes in the circulating immune cells as a predictor of outcomes in patients who have survived cancer. Materials and Methods: A peripheral blood immune-profile evaluation was performed in all the survivors of cancer (n = 66) during their visit to the hospital for regular follow-up and thereafter followed up for two consecutive years for any morbidity or mortality. The changes in hematological and biochemical parameters were evaluated in all the patients. The frequency of circulating lymphocyte cell population i.e., CD3+, CD4+, and CD8+ lymphocytes were analyzed using flow cytometry in the peripheral blood of the patients. The variability in the circulating lymphocytes was correlated with tumor relapse and overall survival (OS). Results: In the study, 47 of the 66 patients with cancer survived at the end of 2 years observation time period, while 19 patients died due to infection related complications and not due to tumor relapse. A significant reduction in the neutrophil (P < 0.0001) and lymphocyte (P < 0.0001) counts were observed in patients who succumbed to the illness within 2 years when compared to the cohorts that were surviving. A statistically significant reduction in the absolute lymphocyte counts (P < 0.004), absolute CD3 (P < 0.0001), CD4 (P < 0.002), and CD8 (P < 0.04) were observed in the deceased group compared to the surviving group. CD4/CD8 ratios between both live and deceased groups did not show any significant difference. Conclusion: This preliminary observational study indicates a correlation of circulatory lymphocytes to OS in survivors of cancer and that it could be a predictive marker.

Na+/H+ exchanger regulatory factor 1 expression levels in blood and tissue predict breast tumour clinical behaviour

Several studies have demonstrated that Na(+) /H(+) exchanger regulatory factor 1 (NHERF1) protein, which is overexpressed and heterogeneously distributed in different stages of breast cancer, could be used as a tumour marker for prognosis in molecular detection strategies. We observed that tumour-infiltrated lymphocytes in the tumour tissue display a high level of NHERF1 staining, in contrast to those present in the contiguous non-involved tissue. Hypothesizing that cancer cells elicit a specific T-cell response associated with the characteristics of the solid tumour, our aim was to evaluate NHERF1 in peripheral lymphocytes from healthy donors and breast cancer patients. NHERF1 levels were analysed in 55 breast cancer patients and 40 healthy donors, and these levels were compared with clinical pathological features. NHERF1 was overexpressed in circulatory peripheral lymphocytes from patients as compared with those from healthy subjects. Furthermore, in both circulatory lymphocytes and tissues, NHERF1 was positively associated with tumour grade, Nottingham Prognostic Index and oestrogen receptor, whereas there was no association with other clinical parameters in either tissue. We propose that NHERF1 measurements in circulatory lymphocytes of breast cancer patients may be a valid method for the prediction of breast cancer occurrence and prognosis, and may have value in the management of cancer patients.

The correlations among serum tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and sialic acids with peripheral lymphocytes in bovine tropical theileriosis

The infection with protozoan parasite Theileria annulata induces changes triggering the activation and/or proliferation of the host lymphocytes. In order to find out the possible correlations among peripheral circulatory lymphocytes, cytokine activities and the level of sialic acids, 50 dairy Holstein cattle, naturally infected with T. annulata, were divided into 4 subgroups according to their parasitemia rates (<1%, 1-3%, 3-5% and >5%). Also, ten non-infected cattle were sampled as control group. Blood samples were taken from jugular vein into acid citrate dextrose-containing tubes for measuring hematological parameters and B and T (CD(4) and CD(8)) cell populations and without anticoagulant for TNF-alpha, IFN-gamma and sialic acid concentrations. Remarkable decreases observed in red blood cells (RBCs), white blood cells (WBCs) and packed cell volume (PCV) in infected cattle compared to healthy ones (P < 0.05). Also, with increase in parasitemia rate, total lymphocytes and monocytes alleviated in the diseased groups. By contrast, total neutrohpils and the concentrations of TNF-alpha, IFN-gamma and total sialic acids were significantly elevated (P < 0.05) in infected animals. Accordingly, the circulatory populations of CD(4) and CD(8) T cells and B cells showed a substantial decrease, while a significant increase was observed in T (CD(4) and CD(8)) cells in cattle infected with <1% parasitemia rates. Decreased circulatory T cell population shows the ineffective responses of T cells to the stimulatory cytokines such as IFN-gamma or TNF-alpha. On the other hand, the elevation of cytokines (particularly IFN-gamma) and sialic acids have presumably an inhibitory role on circulatory B cell population in infected cattle. In addition, a high level of sialic acid concentration indicates the probable role of sialic acid to regulate the parasite-host cell adhesion during sporozoites invasion.

Effect of pretreatment with FTY720 and cyclosporin on ischaemia-reperfusion injury of the liver in rats.

The effect of pretreatment with FTY720 (2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propanediol hydrochloride) or cyclosporin, or both, on neutrophil-mediated injury has been examined by use of a rat model of transient clamping of hepatic flow. Pretreatment with FTY720 alone or with cyclosporin induced a marked reduction of circulatory lymphocytes, whereas the use of these drugs in combination was very effective at suppressing the elevation of the number of peripheral polymorphonuclear neutrophils (PMN) after reperfusion. Pretreatment with cyclosporin, with or without FTY720, significantly reduced hepatic damage, whereas FTY720 alone tended to prolong hepatic damage. Pretreatment of cyclosporin alone, but not in combination with FTY720, significantly reduced the accumulation of PMN and led to lower myeloperoxidase levels in the damaged liver. In conclusion, pretreatment with cyclosporin, with or without FTY720, reduced hepatic damage after warm ischaemia-reperfusion, whereas pretreatment with FTY720 alone tended to prolong this damage.

RhoA protein expression in primary breast cancers and matched lymphocytes is associated with progression of the disease

RhoA protein is over-expressed in breast cancer and other solid tumors and has been used in tumor biopsies as a quantitative tumor marker for progression, stage and prognosis in molecular detection strategies. Measuring protein markers in plasma or blood cells is preferred to tumor biopsies as it represents a minimally invasive, repeatable measurement that can be followed over time. In this study we evaluated the hypothesis that quantitative RhoA protein expression in circulatory lymphocytes is identically associated with the same tumor clinico-pathological features found in biopsies. RhoA protein levels were analyzed by Western blotting in circulating lymphocytes isolated from 52 consecutive patients with breast cancer and in 34 paired breast tumor biopsies from the same case study, and compared with the following clinico-pathological features of the patients: histological grade, tumor size, steroid receptor status, lymphonode status, proliferative activity and prognosis [Nottingham Prognostic Index (NPI)]. We observed that the level of circulatory, peripheral lymphocyte RhoA expression reflected that found in the matched biopsy of the same patient. Furthermore, similarly to previous reports regarding breast cancer tissue biopsies, the level of RhoA protein expression in both biopsies and in circulatory lymphocytes was positively associated with tumor size, grade, proliferative activity of the tumor biopsy and NPI, while there was no significant association of RhoA protein expression with either estrogen- or progesterone-receptor expression. Our study demonstrated that the association of lymphocyte RhoA protein expression with classical clinico-pathological parameters closely corresponded with that observed for RhoA protein expression in the tumor biopsies. We propose that measurement of RhoA expression in the circulatory lymphocytes of breast cancer patients can be used to predict breast cancer occurrence, progression and prognosis and may prove valuable in the management of cancer patients.

PARENTERAL N-3 FATTY ACIDS MODULATE INFLAMMATORY AND IMMUNE RESPONSE IN RATS UNDERGOING TOTAL GASTRECTOMY

This study investigated the effect of n-3 fatty acid (FA)-containing parenteral nutrition on the circulatory lymphocyte subpopulation, intracellular cytokine and leukocyte adhesion molecule expression, and phagocytic activity in rats undergoing total gastrectomy. Normal rats with internal jugular catheters were assigned to normal control (NC) and two experimental groups and received total parenteral nutrition (TPN). At the same time, a total gastrectomy was performed in the experimental groups, whereas the NC group underwent a sham operation. The TPN solutions were isonitrogenous and identical in nutrient compositions except for differences in fat emulsion contents. The NC and one of the experimental groups received a soybean oil emulsion (SO), and the other experimental group received 50% soybean oil and 50% fish oil emulsion (FO). Half of the rats in each respective group were sacrificed 1 or 3 days after surgery or the sham operation to examine their immune response. The results showed that the FO group had a higher CD4 proportion and CD4/CD8 ratio than those of the SO and NC groups postoperatively. The phagocytic activity of peritoneal macrophages was higher in the FO group than in the NC group, but no difference was found between the SO and NC groups 3 days after surgery. The intracellular interferon (IFN)-gamma distribution in the FO group was higher than that of the SO group on postoperative days. Leukocyte adhesion molecule expressions and peritoneal monocyte chemotactic protein-1 levels were lower in the FO group than in the SO group on postoperative day 3. These results suggest that parenterally infused FO did not result in immunosuppression. In addition, FO administration promotes lymphocyte Th1 cytokine production, enhances peritoneal macrophage phagocytic activity, and reduces leukocyte adhesion molecule expression in rats with total gastrectomy.

Immunotherapy for experimental rat autoimmune thyroiditis using a novel immunosuppressant, FTY720

While autoimmune disease needs to be continuously treated via long term, administration of immunosuppressants conventional immunotherapy using drugs such as cyclosporin and tacrolimus may cause adverse effects. Recently, a novel agent, FTY720, which was structurally modified from a natural product, has been shown to have a moderate and different immunosuppressive effect from conventional drugs. In this study, we examined the effect of FTY720 on experimental autoimmune thyroiditis (EAT), which was induced in rats by neonatal thymectomy, followed by subsequent sublethal irradiation. Thyroid stimulating hormone (TSH) was measured before and at the end of drug therapy. Histological and hematological examinations were performed using the samples from sacrificed animals. High TSH levels in the animals returned to the normal range following treatment with FTY720. The severity of the thyroiditis was lower in the FTY720 group than in the control group. FTY720 markedly decreased the number of circulatory lymphocytes, and no infections episodes were observed under this treatment. Thus, FTY720 treatment might be preferred for continuous immunotherapy for autoimmune disease without adverse effects.

Recovery from lymphocytopenia and prognosis after adult extracorporeal membrane oxygenation.

Extracorporeal circulation severely impairs the host immune system. Also decreases in circulatory lymphocytes correlate with greater degrees of surgical damage. In this study, the pattern of recovery from lymphocytopenia after extracorporeal membrane oxygenation was retrospectively evaluated from a prognostic viewpoint. The results showed that the circulatory lymphocyte count of survivors returned to normal levels within 5 days after their being weaned from extracorporeal membrane oxygenation, while the circulatory lymphocyte count of nonsurvivors remained at low levels. Because it is easy to measure the number of peripheral lymphocytes, the changing pattern of the circulatory lymphocytes might be a simple and reliable prognostic factor after extracorporeal membrane oxygenation.

Interleukin-6 and a delay of neutrophil apoptosis after major surgery.

Surgical treatments affect host immune systems. Apoptosis of the circulatory lymphocytes and an elevation of the number of neutrophils are induced by surgery. These alterations are not dependent only on the stress hormone. The course of neutrophilia and the serum concentration of interleukin-6 are given after various surgical treatments. Neutrophil-mediated lung injury is discussed.

Diminished lymphocyte and granulocyte gamma-glutamyltranspeptidase activity in acute lymphocytic leukemia and response to chemotherapy.

gamma-Glutamyltranspeptidase (GGT) activity (per mg protein) in blood lymphoid cells of 27 children with acute lymphoblastic leukemia (ALL) (1.05 +/- 0.15) was significantly below that of controls (2.25 +/- 0.30), became normalized during chemotherapy-induced remission (2.47 +/- 0.26), and was low again (1.59 +/- 0.62) in relapsed subjects. Individual variations in the GGT activity of the blood lymphoid cell fraction (per mg protein) bore a significant inverse correlation to the number of white blood cells (WBC) as well as of blasts per ml blood. Blasts had minimal GGT activity; however, partial GGT deficiency was also exhibited by the microscopically normal circulatory lymphocytes of several patients prior to treatment and in relapsed subjects whose blood was still devoid of blasts. Significantly diminished GGT activity (per mg protein) was found in the blood granulocytes of ALL subjects. This deficit, restored during remission and present again at relapse, varied in magnitude but showed no statistically significant correlation to the different patients' degree of neutropenia. In about one-third of the newly diagnosed or relapsed pre-B ALL children, the circulatory granulocytes' GGT activity was only 10-20% of normal. The results suggest that 1) the presence or absence of this sign of functional maldifferentiation in granulocytes is a factor in the heterogeneity of disease manifestation among subjects with apparently the same type of ALL and that 2) measurement of GGT in the circulatory granulocytes, as well lymphocytes, may be useful for monitoring the efficacy of chemotherapy.

Effect of Beta-Adrenergic Stimulation on the Circulatory Lymphocyte Count: Studies in Normals and in Patients with Chronic Airflow Obstruction

In eight non-allergic patients with chronic airflow obstruction (CAO) and eight age and sex matched, healthy control subjects the circadian variation in circulatory lymphocyte count was studied in relation to serum Cortisol and urinary epinephrine levels. In addition, we investigated the effect of the beta-adrenergic agent terbutaline on the lymphocyte count in two ways: as a long-term effect after 8 days of oral slow-release terbutaline with constant diurnal and nocturnal serum levels in patients, and as a short-term effect by a constant rate infusion of 0.2μg/min over 4hr in normals. Both patients and controls showed similar circadian patterns of urinary epinephrine excretion and lymphocyte counts. Patients with CAO, however, had significantly lower epinephrine levels and significantly higher lymphocyte counts at all hours of observation (every 4 hr from 0800 to 0800 hr the next day), as compared with normal controls. After 8 days of slow-release terbutaline the lymphocyte count in the patient group decreased to levels not significantly different from that of normals. The circadian rhythm of the lymphocytes, however, persisted under terbutaline therapy. No correlation existed between the lymphocyte count modulating factor, serum Cortisol and the lymphocyte count over 24 hr. On placebo infusion in the control persons an increase of lymphocytes over 4hr occurred, as a consequence of circadian rhythmicity. On terbutaline infusion a significant increase of lymphocytes after 1hr was follwed by a decrease to levels significantly below those on the placebo day. The same pattern was found in the leucocyte count. From this study it is concluded that beta-adrenergic stimulation corrects the relative lymphocytosis to counts comparable with normals. Other coinciding factors must regulate, however, the circadian rhythmicity.

Effect of beta-adrenergic stimulation on the circulatory lymphocyte count: studies in normals and in patients with chronic airflow obstruction.

In eight non-allergic patients with chronic airflow obstruction (CAO) and eight age and sex matched, healthy control subjects the circadian variation in circulatory lymphocyte count was studied in relation to serum cortisol and urinary epinephrine levels. In addition, we investigated the effect of the beta-adrenergic agent terbutaline on the lymphocyte count in two ways: as a long-term effect after 8 days of oral slow-release terbutaline with constant diurnal and nocturnal serum levels in patients, and as a short-term effect by a constant rate infusion of 0.2 micrograms/min over 4 hr in normals. Both patients and controls showed similar circadian patterns of urinary epinephrine excretion and lymphocyte counts. Patients with CAO, however, had significantly lower epinephrine levels and significantly higher lymphocyte counts at all hours of observation (every 4 hr from 0800 to 0800 hr the next day), as compared with normal controls. After 8 days of slow-release terbutaline the lymphocyte count in the patient group decreased to levels not significantly different from that of normals. The circadian rhythm of the lymphocytes, however, persisted under terbutaline therapy. No correlation existed between the lymphocyte count modulating factor, serum cortisol and the lymphocyte count over 24 hr. On placebo infusion in the control persons an increase of lymphocytes over 4 hr occurred, as a consequence of circadian rhythmicity. On terbutaline infusion a significant increase of lymphocytes after 1 hr was followed by a decrease to levels significantly below those on the placebo day. The same pattern was found in the leucocyte count. From this study it is concluded that beta-adrenergic stimulation corrects the relative lymphocytosis to counts comparable with normals. Other coinciding factors must regulate, however, the circadian rhythmicity.

In vitro glucocorticoid inhibition of steroid-treated residual circulatory human lymphocytes

Various doses of glucocorticoids given in vivo caused a similar degree of maximal lymphopenia. The sensitivities of mitogen-induced proliferation to the suppressive effects of glucocorticoid added in vitro were studied in residual lymphocytes obtained after steroid injection. Methylprednisolone (MP) administered intravenously depleted circulatory lymphocytes and reduced markedly the proliferative responses of residual cells to mitogens (phytohemagglutinin and concanavalin A) 4 to 8 hr after the injection. The addition of MP in vitro to the residual cells further inhibited the cell proliferation. The degrees of proliferation inhibition induced by in vitro MP were compared in cells obtained at various intervals after MP injection. At each specific mitogen concentration, lymphocytes obtained at various intervals were inhibited to a similar degree by MP in the cultures. There was no evidence that cells obtained at the period of maximal lymphopenia, 4 to 8 hr after MP injection, were more resistant to the inhibition of glucocorticoid added in vitro. Hence, the residual lymphocytes were not “steroid-resistant” in the sense of proliferative responses to T-cell mitogens. These results indicate the mechanism of lymphocyte sequestration is unrelated to the suppressive effects of glucocorticoid on cell proliferation.

Effects of ambient temperatures on clinical and immune responses of pigs infected with transmissible gastro-enteritis virus

Two- to three-months-old pigs infected with transmissible gastroenteritis (TGE) virus showed no clinical response when housed at 30°C, but comparable infected pigs exposed to temperature changes from 30°C to 4°C following infection showed typical signs of TGE. Development of TGE-specific immune responses, as measured by blastogenic response of tissue lymphocytes, occurred at 3 days post-inoculation (DPI) in pigs held at 30°C, but not until 7 DPI in infected pigs held under the adverse conditions. Immunosuppression with corticosteroids resulted in a fall in circulatory T cells, lowering of non-specific blastogenic response of circulatory lymphocytes, and clinical signs of disease when immunosuppressed pigs were infected with TGE virus and held at 30°C. It is suggested that clinical responses to TGE virus infection may be affected by the influence of ambient temperatures on the immune responses of pigs.

A compartmental analysis of circulatory lymphocytes in the spleen.

A tentative model describing the passage of circulatory lymphocytes through the spleen is formulated in accord with known anatomical features. In order to preserve isomorphism between the model and the splenic system, the model is formulated in compartmental form and its design allows alternative routes and modes of lymphocyte transit to be considered. The simultaneous differential equations arising from the model are solved using an analogue computer which also provides the means whereby the performance of the model may be compared with suitable dynamic data drawn from literature. This not only allows the selection of a particular configuration of the model in preference to its alternatives, but also allows the numerical determination of certain unknown parameters. In the case of the rat spleen, best agreement between model and experimental data is obtained when between 10 and 25% of the total lymphocyte flux in the model spleen passes through the marginal zone where the average dwell time of the lymphocytes is about 50 min. The white pulp receives a lymphocyte flux from the marginal zone amounting to about 10% of the total splenic flux and the white pulp lymphocytes are sequestered for a period of 4-6 hr before release to the venous circulation. The red pulp receives 90% of the total splenic flux but the majority of lymphocytes find transit through the red pulp in less than 5 min. The remaining flux of lymphocytes, amounting to 10% of the splenic input, is delayed in transit through the red pulp by 2-3 hr before release to the venous circulation.

Bacterial and Hematological Evaluation of Cattle Exposed to Lethal Gamma Radiation

Hereford cattle were exposed bilaterally to 700 R of gamma radiation at 2 R/min and evaluated for bacterial and hematological alterations. These cattle had survived various radiation insults given approximately 20 months previously. Blood samples collected under sterile conditions showed bacteremia in only two animals 14 days postirradiation. The bacteremia however was transient and could not be detected at earlier or later sampling dates. When the animals were sacrificed the irradiated group consistently yielded greater numbers and genera of bacteria from the liver, spleen, mesenteric lymph nodes, and muscle than their respective controls. Concurrent hematologic examination showed all exposed animals to have a decreased number of circulatory leukocytes, thrombocytes, lymphocytes, and neutrophils. This reduction continued to decrease with time and was not related to the incidence of bacteremia.