Bioelectromagnetics 12:47-56 (1991) Antibody Responses of Mice Exposed to Low-Power Microwaves Under Combined, Pulse-and-Amplitude Modulation B. Veyret, C. Bouthet, P. Deschaux, R. de Seze, M. Geffard, J. Joussot-Dubien, M. le Diraison, J.-M. Moreau, and A. Caristan zy Laboratoire de Bioelectromagnetisme de I’Ecole Pratique des Hautes Etudes: zyx ENSCPB, Universite de Bordeaux I, Talence (B. zyxwvu V., J.J.-D., zyxwv M.I.D., J.-M.M., A.C.), Laboratoire d‘lmmuno-physiologie, Universite de Limoges (C. B., I? D.), and Laboratoire de Neuro-immunologie, Universite de Bordeaux zyxwvu Il, Bordeaux (R. d. S., M. G.), France zyx Irradiation by pulsed microwaves (9.4 zyxwvu GHz, 1 ps pulses at 1 ,OOO/s), both with and without concurrent amplitude modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz, was assessed for effects on the immune system of Balb/C mice. The mice were immunized either by sheep red blood cells (SRBC) or by glutaric-anhydride conju- gated bovine serum albumin (GA-BSA), then exposed to the microwaves at a low rms power density (30 pW/cm2; whole-body-averaged SAR zyxwv - 0.015 W/kg). Sham exposure or microwave irradiation took place during each of five contiguous days, 10 h/day. The antibody response was evaluated by the plaque-forming cell assay (SRBC experiment) or by the titration of IgM and IgG antibodies (GA-BSA experiment). In the absence of AM, the pulsed field did not greatly alter immune responsiveness. In contrast, exposure to the field under the combined-modulation condition resulted in significant, AM-frequency-dependent augmentation or weakening of immune responses. Key words: pulsed microwaves, amplitude modulation, in vivo, immune response INTRODUCTION In vivo effects of pulsed microwaves at low-power densities (< 1 mW/cm2) on the immune system of mammals have been reported or reviewed by many investi- gators [cf., e.g., Czerski et al., 1974; Czerski, 1975; Miro et al., 1980; Kunz et al., 1983; Budd and Czerski, 1985; Chou et al., 1986; Liddle et al., 19861, but research in this area has waned in recent years. We were prompted to initiate investigations on the immune response to microwave irradiation because of information obtained in Bordeaux by biologists who used the equipment of A. Priore [Pautrizel et al., Received for review March 30, 1989; revision accepted October 17, 1990 Address reprint requests to Dr. B. Veyret, ENSCPB, UniversitC de Bordeaux I, 33405 Talence Cedex, France. 0 1991 Wiley-Liss, Inc.