Delayed type hypersensitivity induced by LPF from Bordetella pertussis.

Lymphocytosis Promoting Factor (LPF) obtained from Bordetella pertussis, has the capacity to induce peripheral lymphocytosis in mice and blastogenesis of human lymphocytes in vitro. When this Factor is injected intracutaneously in animals and in humans, it was shown to induce local inflammatory reactions with histological, morphological and chronological characteristics of delayed hypersensitivity. LPF and conventional microbial antigens were tested intracutaneously in 35 patients with carcinoma undergoing immunotherapy and in 15 normal individuals. The results showed that the cutaneous reactions induced by LPF were similar to those of the conventional antigens routinely used to asses cell-mediated immunity. LPF via intracutaneous route did not show any adverse reactions. Histological studies were carried out in mice receiving intracutaneous injections of LPF. The immunological mechanisms involved in the induction of delayed cutaneous hypersensitivity by LPF are discussed.