The paradigm of immune homeostasis between type-1 helper T cells (Th1) and type-2 helper T cells (Th2) has been extensively examined with respect to infectious diseases, autoimmune diseases, or tumor progression. Such studies have mostly relied on the profiling of cytokines/chemokines using animal studies or cell culture-based in vitro tests. No quantitative analyses have yet been systematically performed to determine the relationship between the various immune parameters in in vivo investigations. Using peripheral blood from 55 chicken husbandry workers or grapevine orchard workers, we obtained data for various immunologic markers as follows: proportion of major immune cell subpopulations, concentrations of plasma immunoglobulin subclasses, and levels of cytokines produced from activated peripheral blood mononuclear cells. Correlational analyses were carried out to examine the association between these parameters. As the IFN- γ:IL-13 ratio was strongly associated with the production levels of IFN-γ, TNF-α, and to the IFN-γ:IL-4 ratio, the IFN-γ:IL-13 ratio could prove to be a valuable monitoring index to examine Th1 or Th2 predominance. IL-17 levels correlated well with those of IFN-γ or TNF-α. Plasma levels of IgG4, a typical IgG subclass expressed upon the occurrence of allergic diseases, strongly correlated with IgG1 levels, suggesting the implication of IgG1 in allergic hyperreactivity. The proportion of cytotoxic T cells correlated significantly with levels of IFN-γ, and the proportion of natural killer T cells correlated well with IL-13 levels. These two cell types are sources for the production of IFN-γ and IL-3 respectively; hence, results of this study might provide potential monitoring markers for cytotoxic T cells or natural killer T cell-mediated immunoreactivity. Overall, the present study provides several putative candidates for the surveillance or prognosis of the in vivo alteration of humoral or cell-mediated immunity.