Nonspecific suppressor cell activity and lymphocyte response to β-Lactoglobulin in cow’s milk protein hypersensitivity

β-Lactogloblin (BLG) is clinically the most frequent allergen in cow's milk protein hypersensitivity (CMPH). We therefore assessed its in vitro blastogenic effect on lymphocytes of patients suffering from CMPH. Twenty-two patients aged from 1 to 20 months were investigated, β-Lactoglobulin produced a significantly (p < 0.00003) higher blastogenic response in lymphocytes of patients with CMPH (mean stimulation index 7.7 ± 0.7 SEM) than in 26 age-matched controls (2.7 ± 0.4). This response was age related, being most marked in infants up to 5 months of age. Lymphocyte proliferation following stimulation with BLG can be a useful in vitro test in the diagnosis of CMPH. Because of this augmented lymphocyte response, we considered the possibility of a related defect in immune suppression. Nonspecific concanavalin A-induced suppressor cell activity was assessed in the above patient and control populations. Concanavalin A-induced suppressor cell activity was significantly (p < 0.05) reduced in patients with CMPH. This too was most marked in the first few months of life. We suggest that the development of CMPH may be due to delayed maturation of a suppressor cell population.