Respiratory involvement and immune status in yusho patients.

Clinical and experimental studies on respiratory involvement and alterations in immune status were carried out. Respiratory distress occurring in these patients has improved gradually for 14 years but still remains. Copious expectoration at an early stage of the disease may be related to the fact that a number of discrete polychlorinated biphenyls (PCBs) are distributed throughout the lung parenchyma. For accumulation in the bronchial mucosa, structural requirements and specific dose dependence of PCBs have been clearly shown; however, pathological and physiological studies have indicated that respiratory involvement in yusho is mainly small airway disease that may be caused by involvement of cellular component (Clara cells) in bronchioles and/or associated infection. Respiratory distress is often exacerbated by viral or bacterial infection. Changes in the immune status in PCB and polychlorinated dibenzofuran (PCDF) poisoning are as follows: IgA and IgM in the serum are decreased at an early stage of the disease and then return to normal; suppression of cellular immunity was reported in Taiwanese patients and some may remain in the later stages of the disease, as shown in our patients. PCDFs now appear to be the main causal agents in yusho. Rats given PCDFs showed necrosis of the Clara cells in bronchioles and marked thymus atrophy, while few such changes were noted in rats given PCBs. Therefore, further examination is needed for the difference of the toxic effects between two compounds.


Introduction
Since 1968, patients with polychlorinated biphenyl (PCB) and other chemical poisoning began to appear throughout the western part of Japan. The cause was traced and confined to the contamination of edible rice-bran oil by PCBs used as a coolant in the manufacturing process (1). Since then, the disease has been called "Yusho," which means "the oil disease' Unusual skin lesions and the other symptoms in Yusho or PCB poisoning vary a great deal (2,3). Until a year after onset of the disease, respiratory symptoms had been neglected because of a lack of awareness of their relationship to PCB poisoning. Thereafter, we were asked to participate in a study on clinical, laboratory and pathological findings on respiratory involvement in the patients.
As a result, it has been observed that the incidence of respiratory symptoms correlated well with the concentration of PCBs in the blood and the definite PCB peaks were always detected in the sputa (4). Respiratory distress was often exacerbated by viral or bacterial infection, persisting for more than a half year in about half of the patients examined (4). Therefore, immunosuppressive activity of these toxic compounds was observed clinically and experimentally. Respiratory distress occurring in these patients has improved gradually over 14 years but still remains; and furthermore, three interesting facts were found to add to this field of the study: first, structural requirements for accumulation in the bronchial mucosa reported by Brandt et al. (5,6); second, polychlorinated dibenzofurans (PCDFs) included in the rice oil can be hundreds to thousands of times more potent than PCBs or polychlorinated quaterphenyls (PCQs) as inducers of various clinical manifestations (7); third, the furan moiety was covalently bound preferentially to the nonciliated bronchiolar (Clara) cells (8). Therefore, we review the disease and report new facts in consideration of the above-mentioned problems.

Clinical Study
A total of 401 patients with PCB poisoning form the basis of our study. They were subjected to the following examinations: an assessment of subject symptoms, chest x-rays, pulmonary function, microbial study of the sputum and determination of immunoglobulin levels and PCB concentration and type (4) in serum and sputum. The results of these examinations done prior to 1975 (7 years after the onset of the disease) have already been reported, and a pathological study done on the lungs from seven autopsy cases and from rats given PCBs was also described (4).
In this report, early subjective symptoms and physical findings characteristic to the disease were reviewed in detail, and the clinical course and the latest status in pulmonary function and immunological suppression in the patients observed in February and March 1983 were also described.

Animal Experiments
Male rats of the Sprague-Dawley strain, weighing about 220 g, were given, by gastric intubation, 2.5 mg of Kanechlor 400 (KC 400) in 2 mL of edible oil three times per week (Group I PCBs) and 0.25 mg of PCDF in 2 mL of oil (Group I PCDFs) and only 2 mL of oil (Group I control), and the same dose six times per 2 weeks (Group II PCBs, PCDFs and control). Each group of six animals was killed at 7 days (Group I) and 14 days (Group II) after the first ingestion. Tissues were prepared for light and electron microscopy.

Respiratory Symptoms and Signs
Approximately a year after onset of the disease we were asked to see the patients. About half of the patients complained of expectoration; some showed continual mouthful expectoration and used a lot of tissue paper which filled the waste basket within a few hours. Such patients proved to have high concentration of PCBs in the blood (analysis of blood PCBs in Yusho patients was started in 1973, 5 years after the onset of the disease).
Respiratory physical findings in the patients were quite different from those in usual chronic bronchitics: that is, many patients showed no crackles except for smoking patients, even when they expectorated a mouthful of sputum, and some patients showed wheezes without radiological, physiological or immunological evidence of bronchial asthma or pulmonary emphysema.  in Blood and Sputum Respiratory distress occurring in these patients improved gradually over 10 years after onset of the disease (Table 1), but within 5 years respiratory symptoms persisted in most cases (9), especially in those with high t blood concentrations of PCBs and with signs of chroni-AA cally infected airways. PCB concentration in blood was little changed from 1973 (5 years after the onset of the disease) to 1983 (10). PCB concentration in sputa was about one-third to one-tenth of the blood concentration.
In a 66-year-old male patient with bilateral cicatrical thickening of the pleura due to tuberculosis which healed  the IgA levels in sputum were not low (4). Immunoglobulin levels were again examined in 1980, when all were in normal range (Table 3).
Since T-cells appeared to be sensitive to PCDF poisoning in the animal experiment described below, the effect of PCDF on two T-cell subsets, i.e., suppressor T-cells and helper T-cells were studied. Table 4 shows that the percentage of helper T-cells (OKT-4) was slightly increased but that of suppressor T-cells (OKT-8) was slightly decreased in the patients with higher blood PCB concentration (> 10A). The response to nonspecific mitogen-PHA was also lowered in the same patients. ' Pathologic Changes in the Lungs and Thymus Pathological study of lung specimens from seven autopsy patients disclosed lymphocyte infiltration in bronchial and bronchiolar walls and macrophage infiltration in alveoli, particularly around bronchioles associated with alveolar collapse in four patients dying at 13 to 48 years of age (4). Focal hemorrhage and/or pulmonary edema and pleural and pericardial effusion or adhesion were also detected in three patients who died within 4 ;-. to 12 months after the onset of the poisoning (12,13). e V X Marked hyperemia, atelectasis, and alveolar hemorrhage were noted in a stillborn case (14).
; In rat lungs given PCDFs, necrosis of the Clara cells a.' was seen mildly at a week and clearly at 2 weeks after the start of the experiment (Figs. 1A and 2). Other histologic changes were mild pulmonary edema and 'e ; vascular congestion at 2 weeks (Fig. 1A). These findings were mild in rats given PCBs (Figs. 1B and 3). Rat thymus given PCDFs decreased in size, and microscopic features showed severe atrophy (Fig. 4A), but rats given PCBs showed the same type of changes r i but of less severity (Fig. 4B).

Cause, Clinical Symptoms and Pathophysiological Changes in Yusho
The causative agents proved to be PCBs, PCQs and PCDFs by chemical and activation analysis. Recent studies in mice showed that a number of discrete PCBs were not taken up by the bronchi but were distributed very evenly throughout the lung parenchyma (5). However, specific dose dependence (15) and structural requirements (6) (7), and a furan derivative (4-ipomeanol) that produces a characteristic lesion in several laboratory animal species which is necrosis of the nonciliated bronchiolar (Clara) cells. The initial damage to this cell population appears to be highly selective. Relatively late occurring manifestations of lung toxicity after administration of comparatively large doses of furan derivatives sometimes may include pulmonary edema, pleural effusions, vascular congestion and hemorrhage (8). Lungs of rats given PCDFs in this study also showed the same pathologic features as those in 4-ipomeanol (furan derivative) intoxication.

Alterations in Immune Status
Respiratory distress is often exacerbated by viral or bacterial infection. In the latter, Gram negative bacilli were often detected and found to persist in about half of the cases examined (4).
The changes in immune status in Japanese and Taiwanese patients (16) were almost the same in humoral immune response; that is, IgA and IgM in the serum decreased in both Japanese and Thiwanese patients about 2 years after the onset of the disease, and then returned to normal after 3 years.
Yau-Chin Lu (16) reported low OKT 4/8 ratio (namely, low helper/suppressor T-cell ratio) and enhanced responsiveness to nonspecific mitogen-PHA in Chinese PCBpoisoned patients 3 years after onset. Conversely, our data showed, in Japanese Yusho patients 14 years after onset, high OKT 4/8 ratio and lowered responsiveness to PHA. The differences may be attributed to phenomena in the course of the disease.
Data on the effect of PCBs on the immune mechanism are sparse, although a general lowering of gammaglobulin levels in nonpregnant rodents has been noted by some authors (17)(18)(19), and the suppression of cellular immunity such as the delayed-type skin repsonse to streptokinase and streptodornase was reported in PCBpoisoned patients (20). In our experimental animals, feeding of PCBs caused mild thymus atrophy, and feeding of PCDFs, marked atrophy. As mentioned above, PCDFs are the main causative agents in Yusho. Therefore, further examination is needed to ascertain in detail the difference in effects between PCBs and PCDFs.