PASSIVE-IMMUNIZATION WITH AN ANTI-SUBSTANCE-P ANTIBODY PREVENTS SUBSTANCE-P-INDUCED AND NEUROKININ-A-INDUCED BRONCHOSPASM IN ANESTHETIZED GUINEA-PIGS

In a guinea-pig model of asthma, active immunization against substance P (SP) prevented the development of airways' hyperresponsiveness and reduced bronchospastic responses to SP (iv). The rat-mouse heterohybri doma NC1/34 secretes a specific, rat IgG1, anti-substance P antibody ( alpha-SP Ab) which was isolated and purified by passing supernatant fr om cultures through thiophilic gel. Purity of antibody was about 50% ( SDS-PAGE). The relative affinities of the alpha-SP Ab for SP, neurokin in A (NKA) and calcitonin gene-related peptide (CGRP) were estimated b y ELISA using a constant amount of SP coupled (glutaraldehyde) to bovi ne serum albumin (BSA) to capture the antibody, alone and in the prese nce of increasing concentrations of the neuropeptides. At alpha-SP Ab dilutions of 1 in 5,000 to 1 in 32,000, CGRP did not prevent antibody binding to SP-BSA conjugate bound to the plates, but both SP and NKA p revented binding. In this system, the relative affinity of the alpha-S P Ah, at dilutions of 1 in 5,000 and 1 in 10,000, was about 50 times g reater for SP than NKA. Whether passive immunization with alpha-SP Ab prevented bronchospastic responses to SP and NKA (iv), in vivo, was de termined in groups of anesthetized guinea-pigs by recording pulmonary flow resistance (R(L)) and dynamic pulmonary elastance (E(L)). Injecti on of alpha-SP Ab (iv, 5:1 molar ratio: alpha-SP Ab:SP total dose) did not alter baseline values of R(L) and E(L), but markedly inhibited in creases in R(L) and E(L) induced by SP and NKA (iv) without affecting responses to methacholine (iv). A control, ''irrelevant'' rat IgG-type antibody at a similar concentration had no effect on responses to SP or NKA. These findings indicate that passive immunization with a monoc lonal alpha-SP Ab can prevent the bronchospastic effects of exogenous SP and NKA in guinea-pigs.