Association of elevated blood levels of pentachlorophenol (PCP) with cellular and humoral immunodeficiencies

It has long been suspected that pentachlorophenol (PCP) exerts a damaging i nfluence on the immune system. In this study, the possible relationship bet ween blood levels of PCP and immune function was studied in 190 patients wh o had been exposed for move than 6 mo to PCP-containing pesticides. The pat ients suffered from frequent respiratory infections and general fatigue. Ly mphocyte subpopulations, in-vitro responses to mitogens, allogeneic stimula tor cells, plasma neopterin, cytokines, soluble cytokine receptors, soluble adhesion molecules, and immunoglobulin autoantibodies were determined. A d ose-response relationship between blood levels of PCP and cellular and humo ral immune parameters was established. Blood levels of PCP were associated negatively with (a) total lymphocyte counts (p =.0002), CD4/CD8 ratios (p = .0015), and absolute counts of CD3+ (p <.0001), CD4+ (p <.0001), CD16+ (p < .0001), CD25+ (p.0003), DR+ (p <.0001), CD8+/56+ (p =.020), and CD19+ cells (p =.092); (b) plasma levels of interleukin-2 (IL-2) (p <.0001), soluble l L-2R (p <.0001), IL-6 (p <.0001), IL-10 (p =.0039), interferon-gamma (IFN-< gamma>) (p <.0001), tumor necrosis factor-alpha (TNF-<alpha>) (p <.0001), t ransforming-growth factor-beta(2) (p =.023), soluble IL-1 receptor antagoni st (slL-1RA) (p <.0001), soluble intercellular adhesion molecule-1 (p =.000 3); and (c) immunoglobulin (Ig) M-anti-Fab type autoantibodies (p =.0353). PCP levels were associated positively with (a) number of impaired stimulati on assays per patient (p =.041); (b) number of circulating CD11b+ monocytes (p =.0015); and (c) plasma levels of neopterin (p <.0001), IL-4 (p =.020), and sIL-6R (p =.020). Compared with patients who had PCP plasma levels tha t were less than or equal to 10 <mu>g/l, patients with brood levels of PCP that exceeded 10 mug/l experienced the following more often: low numbers of total blood lymphocytes (p.054), CD3+ (p =.0014), CD4+ (p =.0001), DR+ (p =.0003), CD16+ (p.0033), and CD25+ cells (p =.0033). In addition, the same aforementioned patients experienced the following more frequently: undetect able plasma levels of IL-2 (p =.0057), IL-6 (p =.042), IL-8 (p =.038), IL-1 0 (p.0001), TNF-a (p =.0062), and IFN-gamma (p =.016); and impaired in-vitr o responses of lymphocytes (p=.071). The authors concluded that increased b lood levels of PCP were associated significantly with cellular and humoral immunodeficiencies. Recurrent respiratory infections and general fatigue co uld originate from PCP-associated immunosuppression.