Thirty=seven human volunteers were exposed to card-generated airborne cotton dust from washed or unwashed high-microbiological cottons. The humoral immunologic status of the subjects was defined in terms of serum levels of IgG, IgA, IgM, and IgE. No group differences from published normal levels were noted. Specific IgE to a panel of 6 allergens was assessed, and one subject had detectable IgE to only one allergen. Separation of the subjects into greater-reactors and lesser-reactors based on acute inflammatory mechanisms. Serum complement changes after cotton dust inhalation suggest activation of the alternative complement pathway, and serum alpha(1)-antitrypsin elevations suggest inflammatory reactions.