Age-related changes in protein concentrations in serum and respiratory tract lavage fluid obtained from cats

Total protein concentrations was determined in serum, bronchoalveolar lavage (BAL) fluid, and nasal flush fluid obtained from specific-pathogen-free cats from birth to maturity and from adult conventionally raised cats. Protein components were analyzed by immunoelectrophoresis and isoelectric focusing. Albumin, and alpha-, beta-, and gamma-globulins were among the proteins identified in BAL fluid, and their isoelectric point ranged from 3.1 to 5.1. gamma-Globulin was not detected in serum or BAL fluid of newborn kittens before they had ingested colostrum. By day 3 after ingestion of colostrum, IgG was detected in high concentration in serum and was the predominant immunoglobulin in serum and BAL fluid of older cats. Nasal flush fluid from cats greater than 6 months old contained albumin, and alpha-, beta-, and gamma-globulins, with IgA being the predominant immunoglobulin. Total protein concentration in nasal flush fluid increased progressively with increasing age, and albumin was the predominant protein. Protein concentration was significantly (P less than 0.01) higher in BAL fluid from conventionally raised adult cats than in that from specific-pathogen-free cats.