Changes in T cell subpopulations in lead workers.

To investigate the effects of lead on the human immune system, we analyzed T cell subpopulations and B (CD19+) cells in peripheral blood in 71 male lead workers. They were engaged in manufacturing lead stearate in a chemical factory, aged 20 to 74 (mean 48) years. Their blood lead concentrations (PbB) were between 7 and 50 (mean 19) micrograms/dl. The control group consisted of 28 "healthy" male volunteers without a history of occupational exposure to lead or other hazardous substances, aged 33 to 67 (mean 55) years. In comparison with the controls, a significant reduction in the number of CD3+CD45RO+ (memory T) cells and a significant expansion in the percentage of CD8+ cells in the lead workers were found. There was a significant positive correlation between the percentage of CD3+CD45RA+ (naive T) cells and PbB in the lead workers. It is suggested that CD45RO+ memory T cells may be most susceptible to the effects of lead on T cell subpopulations.

Elevated serum levels of pantropic p53 proteins in chromium workers.

OBJECTIVES: This study investigated the possibility of applying serum pantropic p53 proteins in molecular epidemiologic studies, as a biomarker of environmental carcinogenesis. The serum levels of pantropic p53 proteins were determined in workers with past exposure to hexavalent chromium compounds. METHODS: Thirty-one male workers occupationally exposed to hexavalent chromium compounds in the production of chromium compounds for 0 to 23 years served as the exposed group. The referents were 10 volunteers without work-related exposure to chemicals. In the determination of pantropic p53 proteins, commercially available kits for enzyme-linked immunosorbent assay were used which quantitatively detected both mutant and wild-type human p53 proteins. RESULTS: The serum level of pantropic p53 proteins was in the range of 116.4 to 1122.6 pg/ml for the exposed workers and of 117.4 to 305.8 pg/ml for the referents. Nineteen percent of the exposed workers had a high p53 protein level (6 out of 31) when compared with the referents. All but 1 of the 6 workers had been occupationally exposed to chromium compounds for more than 11 years. Two of the 3 workers with a past history of lung cancer also showed high levels. CONCLUSIONS: Our findings confirm that the application of p53 proteins as a biomarker of environmental carcinogenesis merits further exploration.

Changes in natural killer cell subpopulations in lead workers.

To investigate the effects of lead on human immune system, we analyzed T cell subpopulations (CD4+, CD8+ and CD3+ cells), natural killer (NK) cell subpopulations (CD16+ and CD57+ cells) and B (CD19+) cells in peripheral blood in 29 male lead workers. All were engaged in manufacturing lead stearate in a chemical factory. They were aged 23-74 (mean 49) years. Their blood lead concentrations (PbB) were between 7 and 35 (mean 18) micrograms/dl. They were divided into two groups according to their PbB: a high-PbB group (> or = 20 micrograms/dl), and a low-PbB group (< 20 micrograms/dl). The control group consisted of 19 "healthy" male workers without a history of occupational exposure to lead or to other hazardous substances, aged 48-67 (mean 58) years. The number and percentage of CD16+ cells in the high-PbB group were significantly lower than those in the controls and in the low-PbB group. There was significant negative correlation between the number of CD16+ cells and PbB in the lead workers. The percentage of CD8+ cells in the high-PbB group was larger than that in the controls and in the low-PbB group. It is suggested that the CD16+ NK cell should be a major site of the effects of lead on lymphocyte subpopulations.

Subclinical vestibulo-cerebellar, anterior cerebellar lobe and spinocerebellar effects in lead workers in relation to concurrent and past exposure.

By computerized static posturography, the subclinical effects of past and concurrent lead absorption on the vestibulo-cerebellum (lower vermis), anterior cerebellar lobe and spinocerebellar afferent pathway were examined in 49 male chemical factory workers exposed to lead stearate (lead workers). Their concurrent blood lead (BPb) concentrations ranged from 7 to 36 (mean 18.0) microgram/100 g. In the past, their maximum BPb ranged from 11 to 113 (mean 47.7) micrograms/100 g; mean BPb was 7-52 (mean 23.5) micrograms/100 g; and cumulative BPb, defined as mean BPb x years of exposure, was 15-1268 (mean 390.6) micrograms.year/100 g. Control subjects were 23 healthy male workers who had never been occupationally exposed to lead. The postural sway of high (2-4 Hz) and low (1 Hz or less) frequencies with eyes open for lead workers was significantly greater than that for controls in the medio-lateral (right-left) and anterior-posterior directions. Similarly, the sway of high and low frequencies with eyes closed was significantly larger in lead workers than in controls in the medio-lateral direction. Results of stepwise multiple regression analysis indicated that the sway with frequencies of 0.5-2 Hz with eyes open was related to concurrent BPb in the anterior-posterior direction. With eyes closed the sway of high frequency was significantly related to mean BPb in the past in the medio-lateral direction. The pattern of the changes suggests that the vestibulo-cerebellum, anterior cerebellar lobe and spinocerebellar pathway are asymptomatically affected by lead. It appears that the change in the vestibulo-cerebellum reflects concurrent lead absorption, while on the other hand, that in the anterior cerebellar lobe reflects past lead absorption.