In the light or contemporary understanding of the T- and B-systems of immunity, however, the question of the effect of pesticides on the organism has not yet received adequate study, and there is a lack of information concerning the role of the lymphocyte sub-populatons in the pathogenesis of developing intoxications.

The aim of the present work was to study the quantitative characteristics and the functional condition of the T- and B-systems of immunity in sufferers from different forms of pesticide intoxication.

We examined people from various professions (kolkhoz and sovkhoz workers, agronomists, mechanics. aeroplane engineers, etc.) aged between 22 and 50, with periods of employment of between 5 and 15 years. The control group comprised 45 persons in good health. During their work, the persons examined came into contact with a mixture of pesticides, mainly of the organochlorine and organophosphorus groups, causing the development of multiple intoxication by these pesticides.

Depending on the clinical picture, the persons examined were divided into 3 groups.
The 1st group consisted of cases of isolated manifestations of the actions of pesticides (pre-morbid stage of intoxication). In the members of this group,

examination revealed certain deviations in the state of health which showed signs of being initial disturbances of the activity of the nervous system and liver and dis-coordination of various metabolic processes. The 2nd group comprised cases of chronic multiple pesticide intoxication. In the clinical picture for these persons, alongside the basic syndromes which were of the type of functional and organic forms of damage to the nervous system and the liver, There were also disturbances in the cardio-vascular and respiratory systems and in the functional condition of the kidneys, as well as deviations in a number of metabolic processes. The 3rd group comprised cases with a history of acute pesticide intoxication. Pathology of the nervous system of a functional-organic nature and pathology of the liver (hepatopathy) were characteristic in the clinical picture.

The state of the T-system of immunity was assessed using tests for spontaneous rosette-formation (Jondal and co-authors) and blastic transformation of lymphocytes. The B-system of immunity was assesssed by determining the quantity of B-cell-rosette-forming lymphocytes revealed by the complementary rosette-formation test (Mendes and co-authors), and the level of serum immunoglobulins (IgG, IgA, IgM) determined by Mancini's method of radial immunodiffusion.

To assess the immunological status, we counted both the relative and the absolute number of immunocompetent cells circulating in the blood. We also studied the content of T- and B-cell-rosette-forming lymphocytes in relation to the number of attached erythrocytes (Yu. A. Grinevich), separating "incomplete" (]ymphocyte with 3-5 attached erythrocytes) from "complete" (more than 5 erythrocytes on surface of lymphocyte) reaction. To study the level of possible activation of T-lymphocytes, we simultaneously determined the total number of T-cell-rosette-forming lymphocytes and the number of "early" or active rosettes.

The tests performed on cases of both isolated and extensive forms of organochlorine and organophosphorus pesticide poisoning revealed a considerable suppression of the T-system of immunity; a decrease in the relative and abso1ute number of T-cell-rosette-forming lymphocytes and a suppression of their functional activity. Simultaneously an activation of the B-system of immunity was observed; there was an increase in the number of B-cell-rosette-forming lymphocytes and a rise in the IgG and IgA content.

Table 1 gives the data for the quantitative content and functional activity of the T-lymphocytes in relation to the degree of intensity of the compound acion of the pesticides on the employee's organism. The results show that even for the members of the 1st group (pre-morbid stage of intoxication) there was a statistically significant decrease in the relative and absolute content of T-cell-rosette-forming lymphocytes. The decrease in the T-lymphocytes in the peripheric blood took place basically through a reduction in the number of lymphocytes absorbing more than 5 sheep red cells on their surface, i.e. "complete" rosettes. The blastic transformation of lymphocytes was consistently less in comparison with the control group.

In the 2nd group of persons examined (with chronic multiple pesticide intoxication), we found the most marked decrease in the number of T-lymphocytes and a suppression of their functional condition. In the persons examined in this group, we discovered the least number of complete" rosettes, and in a number of cases the lymphocytes were incapable of forming rosettes with 5 sheep red cells and more. The decrease in the functional properties of the T-lymphocytes was accompanied by a suppression of the blastic transformation of lymphocytes in response to phytohaemagglutinin (PHA), and also by a decrease in the number of active rosette-forming lymphocytes. Thus in healthy people the number of active T-cell-rosette-forming lymphocytes was 35.2 +_ 2.1%, while for intoxication cases the number was 23 +_ 1.2%.

The decrease in the percentage and absolute content of T-lymphocytes and the suppression of their proliferative capacity under the influence of phytohaemagglutinin was also clearly seen in the members of the 3rd group (with acute intoxication at a time in the past).

The results of determination of the indices for the B-system of immunity are shown in table 2. This material allows us to state that with all forms of action of pesticides on the organism a significant increase in both the percentage and the albsolute content of B-cell-rosette-forming lymphocytes is observed, and this is most marked in sufferers from chronic multiple intoxication. At the same time an increase in the level of IgG and IgA is observed. The IgM content does not vary significantly in comparison with the control group.

Therefore the tests performed permit the conclusion that in sufferers from various manifestations of the effect of pesticides, a considerable suppression of the T-system and a similtaneous activities of the B-system of immunity are observed.

It was established that the content of T- and B-lymphocytes in the peripheral blood varies in relation to the clinical symptoms of intoxication.

The decrease in the number of T-lymphocytes and tbe suppression of their functional activity are probably caused by the high degree of sensitivity of this type of cell to the action of chemical agents, which is indirectly borne out by the fact that with chronic multiple intoxication the depression of the T-system is at its most profound. Here there is not only a quantitative deficit. but also a functional inadequacy of the T-lymphocytes, expressed as a suppression of the reaction of blastic transformation of lymphocytes, a reduction in the level of lymphocytes forming "comp1ete" rosettes with sheep red cells, and a decrease in the number of T-cell-rosette-forming lymphocytes. The increase which was observed in the content of B-lymphocytes may be a result of an insufficiency (depression) in the sub-population of T-suppressors (Bach). The activation of the B-system of immunity additionally confirms the previous supposition of the development of autoimmune processes with pesticide intoxication (A.I. Nikolayev; L.A. Katsenovich and co-authors).

The data obtained permit the assumption that in chronic intoxication sufferers it is not a general immunodepression that is observed, but a T-immuno-deficiency condition associated with prolonged quantitative and functional suppression of the T-system of immunity and progressive autoimmunisation of the organism. The existence of a certain deficit in thc immune system in turn requires a correction to this link in the chain, as was suggested previously in the literature (O. C. Alekseyeva, 1979 ).

This demonstrates that assessment of the state of the T- and B-systems of immunity may be usefully employed in cases of occupational diseases, particularly pesticide intoxications, for diagnostic purposes, and also to assist in developing methods of pathogenic therapy aimed at correcting the disturbed link in the immune system.

REFERENCES

1. Grinevich Yu. A. -Zh. mikrobiol., 1978. No. 9. p. 105-109.

2. Katsenovich L.A.. Nuritdinova N.F.. Ismailova K.A. et al. -In the book :
Respublikanskaya nauch. konf. po probleme gigieny. v usloviyakh Uzbekistana. Materialy. (Scientific conference of the Republic on the question of hygiene under the conditions prevailing in Uzbekistan. Conference reports. ). Tashkent. 1970, p. 218-225.

3. Nikolayev A.I., Subkhankulova F.B., Celler I.C. FarmaKol. i toksikol., 1970. No. 6. p. 737-741.

4. Ruzybakiev R.M., Ataulakhanov R., Gorelov D.E. - In the book: Sbornik nauch. - issled. rabot TsNIL medVuzOV Uzbekistana. (Collected scientific research works of the Central Scientific Research Laboratory of the Medical Institutes of Uzbekistan). Samarkand, 1974, p. 105-106.

5. Bach J.F. - Ann. Immunol., 1977, v. 128, p. 537-540.

6. Jondal M. et al. - J. exp. Med., 1972, v. 136, p. 207-215.

7. Mendes N.F. et al. -J. Immunol., 1973, v. 111, p. 860-867.

Dated 24/7/2007

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