High prevalence and high titers of LAV/HTLV-III antibodies in healthy hemophiliacs in the midwestern United States.

Twenty-eight patients from the Nebraska Regional Hemophilia Center were studied for the prevalence and titers of antibodies to lymphadenopathy-associated virus/human T cell lymphotropic virus type III (LAV/HTLV-III) and for clinical symptoms of possible progression to the acquired immune deficiency syndrome (AIDS). Ten of 18 (56 percent) patients with hemophilia A who were frequently treated with commercial factor VIII concentrate were seropositive for LAV/HTLV-III antibodies as determined by immunofluorescent study and Western blot testing. Of the four factor VIII-deficient patients who were seronegative, one had received only heat-treated factor VIII concentrates, two had received only cryoprecipitate, and one had received no transfusions since 1983. None of the patients treated only with factor IX concentrate, volunteer donor plasma, or cryoprecipitate had LAV/HTLV-III antibodies. In nine of 10 seropositive hemophiliacs, titers of serum antibodies to LAV/HTLV-III ranged from 1:1,280 to 1:10,240, indicating a strong immune response against LAV/HTLV-III antigens and/or persistent infection with the virus. Serum from seropositive hemophiliacs interacted on Western blot testing with all the major LAV/HTLV-III polypeptides, including envelope proteins gp 42 and gp 120. Despite the possible exposure to LAV/HTLV-III during the past four years, none of the patients in this group had symptoms suggestive of progression towards AIDS. Whether or not immunity to the AIDS retrovirus developed in this group of patients remains to be determined.