Age-related changes in the proliferative kinetics of phytohemagglutinin-stimulated lymphocytes. Analysis by uptake of tritiated precursors of DNA, RNA and proteins, and by flow cytometry

Mitotic index maximization with no effect on radiation-induced dicentric chromosome frequency

PURPOSE

The dicentric chromosome (Dic) assay, which is the gold standard for biological dose assessment in radiation emergency medicine, requires an analysis of at least 500 lymphocyte metaphases or 100 Dic aberrations. Therefore, peripheral blood culture conditions able to obtain a high frequency of metaphases for efficient dose evaluation should be optimized. However, the type of blood cultures [i.e. whole blood (WB) or isolated peripheral blood mononuclear cell (PBMC)-culture] and blood volume differ between biodosimetry laboratories. The purpose of this study is to investigate the blood volume at which a high mitotic index (MI) is obtained in peripheral WB-culture and isolated PBMC-culture, and to examine the possible effect of blood volume on radiation-induced Dic frequency.

MATERIALS AND METHODS

Peripheral blood was collected from three healthy donors with their informed consent. The complete and differential blood counts were performed using an automated hematology analyzer. After blood count, peripheral blood was irradiated with 0 or 2 Gy X-ray. Blood was cultured with phytohemagglutinin (180 μg/ml) and demecolcine　(0.05 μg/ml) for 48 h. The MI and Dic frequency were analyzed in 5, 10, 15, 20, 25, and 30% WB-cultures and 0.6, 1.2, 1.8, 2.4, 3.0, 3.6, and 4.2 ml WB-equivalent PBMC-cultures.

RESULTS

In WB-culture, MI showed the highest value (∼22%) in 5-15% WB-culture and then gradually decreased to ∼9% with 30% WB-culture. MI peaked at 36 and 31% in 1.8 and 2.4 ml-WB equivalent volumes for PMBC-cultures, respectively. MI progressively decreased as the amount of PBMCs increased. Although individual differences were observed in the MI values among the three subjects, all the subjects showed the same tendency and higher MI was seen in PBMC than WB-cultures. However, these factors had no significant impact on the yield of Dics. In all culture conditions, the estimated dose calculated based on the Dic frequency was equivalent to the absorbed dose of ex vivo X-ray-irradiated blood.

CONCLUSION

While MI was affected by the blood culture type and the volume of cultured blood, Dic yield did not differ significantly between these conditions. These results could be used by relevant laboratories to optimize MI in certain circumstances.

Are infants unique in their ability to be "functionally cured" of HIV-1?

The recent report of an infant that appears to have achieved a "functional cure" of HIV-1 following receipt of antiretroviral therapy (ART) within 30 hours of birth raises many questions: was the child infected? Was this result due to unique features of this particular infant's immune system, the immune system of infants or the very early initiation of effective ART? In this manuscript, we discuss the pathogenesis of HIV-1 in infants, highlighting the unique features of infant immune development and how these may inform efforts to cure HIV infection. We will also compare the path to infant "cure" to cures in adults.

Gene expression changes in normal haematopoietic cells

The complexity of the healthy haematopoietic system is immense, and as such, one must understand the biology driving normal haematopoietic expression profiles when designing experiments and interpreting expression data that involve normal cells. This article seeks to present an organised approach to the use and interpretation of gene profiling in normal haematopoiesis and broadly illustrates the challenges of selecting appropriate controls for high-throughput expression studies.

Micronuclei in peripheral blood lymphocytes and buccal epithelial cells of Polish farmers exposed to pesticides

In this biomonitoring study, we investigated whether an occupational exposure to a complex mixture of chemical pesticides produced a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Forty-nine male workers exposed to pesticides, from an agricultural area of Malopolska Region in Southern Poland, together with 50 men from the same area without indication of exposure to pesticides that served as controls, were used in this investigation. No statistically significant differences in the frequencies of cytogenetic damage were detected between exposed and control individuals, for either type of cells. The multiple linear regression analysis in the case of lymphocytes indicated that the studied cytogenetic endpoints were inversely influenced by alcohol; whilst a negative binomial regression, in the case of buccal cells, indicated that the MN values were directly influenced by the ingestion of red meat. An inverse negative relationship between the cytokinesis-block proliferation index and age, and a significant increase of miscarriages due to the exposure to pesticides were also observed.

Stimulatory effect of saponin from Panax ginseng on immune function of lymphocytes in the elderly

We used the saponin Rg1 extracted from Panax ginseng to study its effects on lymphocytes of 10 young and 19 elderly persons. The proliferative response of lymphocytes cocultured for 72 h with PHA and saponin was measured by using MTT method and the 3H-TdR incorporation procedure. PHA and Rg1 had stimulative effects on the phenotype of lymphocytes (P < 0.001). Rg1 also increased the fluidity of lymphocyte membrane of the aged (P < 0.001). The CD25 and CD45RA positive cells of lymphocytes in the elderly were lower than those of the young people, 8.6% +/- 2.7% vs 10.43% +/- 3.5%; 20.95% +/- 15.5% vs. 50.86% +/- 4.2%, respectively. More CD45RO positive cells (41.5% +/- 13.9%) than CD45RA positive cell lymphocyte populations were seen in the aged. The CD45RO positive cells of the young people were 39.63% +/- 3.2%. We discussed the cause of declined immune function of lymphocytes of aged person and the mechanism of the effect of P. ginseng on lymphocytes.

Human lymphocytes incubated in vitro share multiple characteristics with geriatric-derived lymphocytes: a potential in vitro model for aging?

Aging involves a complicated set of parallel reactions that result in multiple cellular and organismic changes and may eventuate in chronic illness. In the immune system, several alterations that correlate with age have been established. In the present study, we report the results of incubating lymphocytes in vitro in whole blood and, employing measures known to be age-dependent, compare these cells 'aged' in vitro with cells from geriatric patients aged in vivo. Cells from blood aged in vivo and incubated in vitro share a number of common characteristics that include decreased growth capacity, shifted growth patterns, increased suppression by adherent cells, decrease in CD5 surface antigen, similar responses to addition of exogenous IL-1, IL-2, PGE2, or indomethacin, and similar production of PGE2. Differences found between in vivo aging and in vitro incubation are IL-2 plasma levels and IL-2 production by activated cells monitored in conditioned minimal medium. Based on these observations, this in vitro system provides a simple method to generate cells that exhibit a very significant subset, but not all, of the characteristics associated with in vivo aging in lymphocytes.

Sister-chromatid exchanges and their distribution in human lymphocytes in relation to age, sex and smoking

The effects of age, sex and smoking on sister-chromatid exchange (SCE) frequency and distribution in human lymphocytes were assessed by means of multiple linear regression. Differences in SCE scores were associated with all above variables: SCE increased with age and cigarette smoking intensity, and higher SCE frequencies were observed in females. Changes in SCE distribution were associated with age and smoking: the ratio of sample variance to sample mean (heterogeneity index) increased with age and smoking intensity. Cell proliferation kinetics, as measured by replication index, inversely correlated with age. Monte Carlo methods were used to show that in the occupational study, analysis of 20-50 persons per group and 25 cells per person may be recommended.

HIV-1 reverse transcription in cord blood lymphocytes: implications for infection of newborns

We previously demonstrated that progeny virions are not produced after infection of adult quiescent peripheral blood lymphocytes (PBLs) by human immunodeficiency virus type 1 (HIV-1). Molecular analysis revealed that the nonproductive nature of this infection is due to failure to complete reverse transcription of the viral genome. In this study, we examined HIV-1 reverse transcription in quiescent lymphocytes from umbilical cord blood (CBLs). Using the polymerase chain reaction (PCR) to detect the presence of reverse transcription intermediates, we found that as in PBLs from adults, reverse transcription is not completed in quiescent CBLs; instead, a partial reverse transcript is formed. Quantitative PCR analysis also showed that fewer partial reverse transcripts were found in CBLs than in PBLs. Although the relevance of this restriction in reverse transcription to vertical transmission is unclear, these data suggest that the rapid progression of disease in infected children is not due to increased permissiveness of the lymphocytes of newborns for HIV-1 infection.