A six-year follow-up of antibody levels against microbes present in the farming environment in a group of dairy farmers in finland.код для вставкиСкачать
American Journal of Industrial Medicine 103W-309 (1986) A Six-Year Follow-Up of Antibody Levels Against Microbes Present in the Farming Environment in a Group of Dairy Farmers in Finland Marja-Leena Katila, MD, Tarja Ojanen, MSC, and Rauno Mantyjarvi, MD Key words: hay dust, moulds, sensitization, ELISA titers A group of 325 dairy farmers and 107 rural, nonfarming controls (N = 432), which were studied 6 years earlier for respiratory symptoms and antibodies against known farmer’s lung (FL) antigens [Katila, 19791, were restudied by a symptom questionnaire and by antibody analysis. Ninety percent of the farmers and 71 % of the control group were reached for reevaluation. Serum samples of the two surveys were tested for IgG antibodies against Micropolysporu fueni (Mf), Themactinomyces vulgaris (Tv) , Aspergillus umbrosus (Au), and Aspergillus fimigutus (Af) using ELISA technique [Ojanen et al, 19801, which allows quantitation of antibody levels. Sensitization, when measured by antibody titers, varied greatly in respect to different microbes (Table I). High antibody titers against Au and Mf were more common in farming men and women than in the controls (p < 0.001 and < 0.05, respectively). High antibody titers against Af were equally common in all study groups, and those against Tv were equally or more common in controls than in the farming men and women. The levels of specific IgG against the four microbes were measured from the two serum samples of each person. The majority of farmers (70%) (Table 11) and controls (74%) had no significant changes in antibody levels against any of the studied microbes. Elevations in antibody levels against one or more of the test antigens were detected in 20% and decreases in 11% of the farmers and in 20% and 14% of the controls, respectively. In the farmers, Aspergillus antibody levels changed more (24%) than antibody levels against actinomyces (12%). Some persons had both rises and falls in antibody titers against different microbes, but this was uncommon. In the farmers, decreases in antibody titers were found more often in older age groups and in those persons who had quit farming (p c 0.01) (Table II). In the entire farming population, decreases were detected in 29% of the farmers retired for illnesses compared to 8 % of those farming throughout the follow-up period and 10% of those having stopped because of older age or reasons other than illness. Decreases Department of Clinical Microbiology, Kuopio University Central Hospital, Kuopio, Finland. Address reprint requests to Dr. Marja-Leena Katila, Mycobacterium Reference Unit, Public Health Laboratory Service, University Hospital, Wales, Cardiff CF4 4XW, UK. Accepted for publication January 16, 1986. 0 1986 Alan R. Liss, Inc. 308 Katila et a1 TABLE I. Prevalence of High Antibody Titers in Farmers and Controls (1975) High antibody titer against Men Farming Control (N = 151) (N = 44) Au ( 2 2.50) No. % Af ( 2 2.80) No. % Mf ( 2 2.80) No. % Tv ( 2 3.90) No. % Women Farming Control (N = 138) (N = 36) Total (N = 369) Significance: farmers vs controls p < 0.01 54 36 2 5 75 54 3 8 134 36 34 22 10 23 35 25 9 25 88 24 NS 19 13 4 9 29 21 2 6 54 15 p < 0.05 16 11 12 27 30 21 9 25 67 18 p < 0.05 TABLE II. Changes in Antibody Levels by Changes in OccupationalStatus in the Farming Population (1975-1981) Occupational status in the second survey Farming No. % Increasea Decreasea No change Total 45 22 17 8 149 72 208 6 14 12 29 21 64 42 8 20 4 10 29 71 41 59 20 p = 0.05 33 11 p < 0.01 205 70 29 1 Retired for illness No. % Changed occupation or on pension No. % Total No. % Significance aSome persons had both increases and decreases against different microbes. in Aspergillus antibodies had the closest association with these occupational changes, especially in women aged 30 to 65 years by the end of the follow-up period (p C 0.001). In contrast to decreases, increases in antibody levels were more frequent in younger age groups, being found in 31 % (4/13) of farmers under 31 years, in 25% (28/114) of those aged 31-50 years, and 14% (19/138) of those aged 51-65 years. There was an association between onset of respiratory symptoms in previously asymptomatic farmers and rises in antibody levels. Of the 34 who began to experience dust-related symptoms, 12 (35%) had rises in antibody levels compared to 27 (18%) of those 146 who had no symptoms in the second survey. The ELISA method is very suitable for antibody measurements in environmental microbial exposure. In view of this 6-year follow-up, the degree of sensitization when Six-Year Follow-Up of Antibody Levels 309 expressed as titers was surprisingly stable in constantly exposed “healthy” farmers. Rises in antibody levels were more common in the younger age groups, and levels seemed to have an association with the onset of respiratory symptoms in previously asymptomatic farmers. Decreases in antibody titers against all microbes but especially against Aspergilli were associated with definite cessation of exposure only. In those continuously exposed, the association between specific IgG antibody titers, level of exposure, and respiratory symptoms is very complex. According to preliminary experiences, changes in specific IgG subclasses, as well as in other immunoglobulin classes, may offer some advantages for diagnostic work in this field. REFERENCES Katila M-L (1979): “Respiratory Disease in a Farming Population. A Sero-Epidemiological Survey of Farmer’s Lung and Chronic Non-Specific Lung Disease Among Dairy Farmers in Eastern Finland. PhD Thesis, University of Kuopio, 1979. Ojanen TH, Katila M-L,Mantyjiirvi RA (1980): The use of enzyme-linked immunosorbent assay (ELISA) in the diagnosis of farmer’s lung. Allergy 35537-542.