Immunologic aberrations, HIV seropositivity and seroconversion rates in patients with hemophilia B

Because there have been reports that factor IX concentrate is less immunosuppressive and therefore factor IX users have less immunologic aberrations, we have studied a group of 22 patients with hemophilia B and six patients with factor VIII deficiency and high titer inhibitors with respect to lymphocyte numbers and function, human immunodeficiency virus (HIV) serology, and factor usage. This group was compared to 111 patients with hemophilia A and a group of 28 healthy male volunteer controls. When the study began in 1983, the majority of patients with hemophilia B and with higher titer factor VIII inhibitors were seronegative, 77% and 83% respectively, as compared to only 30% of patients with hemophilia A. At that time the factor IX users also had milder immune aberrations than the hemophilia A group. However, with time and increasing clotting factor concentrate usage, seroconversion and more striking abnormalities in immune function have occurred in the hemophilia B group. In a subgroup of 16 patients with hemophilia B studied twice, the incidence of seropositivity increased from 31% in 1983 to 69% in 1985. We thus conclude that factor IX concentrate in itself is not less immunosuppressive than factor VIII concentrate. Seroconversion in factor IX concentrate users appears to be lagging behind seroconversion in factor VIII concentrate users, perhaps secondary to the lower cumulative dosage of concentrate that patients with hemophilia B utilize.     

Antibodies reactive with human T cell leukemia viruses in the serum of hemophiliacs receiving factor VIII concentrate

The third member of the family of T cell leukemia viruses (HTLV III) has been proposed as the primary etiologic agent of the acquired immunodeficiency syndrome (AIDS). A high risk of AIDS has been reported among patients with hemophilia, particularly those with factor VIII deficiency who receive commercial clotting factor concentrates. In a prevalence survey conducted between September 1982 and April 1984, initial serum samples from 74% of hemophiliacs who had ever been treated with commercial factor VIII concentrate, 90% of those frequently treated with factor VIII concentrate, and 50% of those treated with both factor VIII and factor IX concentrates had antibodies reactive against antigens of HTLV III, compared with none of the hemophiliacs treated only with factor IX concentrate or volunteer donor plasma or cryoprecipitate. Two of the seropositive patients have developed AIDS-related illnesses, and a third patient died of bacterial pneumonia. One initially seronegative patient developed antibodies against HTLV III during the study and is currently well. The predominant antibody specificities appear directed against p24 and p41, the presumed core and envelope antigens of HTLV III, suggesting that factor VIII concentrate may transmit the p24 and p41 antigens of HTLV III. However, the presence of infectious retroviruses in clotting factor concentrates and the effectiveness of screening and viral neutralization procedures remain to be determined.     

Abnormalities of lymphocyte subsets are correlated with concentrate consumption in asymptomatic Italian hemophiliacs treated with concentrates made from American plasma

Eighty-three symptom-free hemophiliacs were studied clinically, serologically and by in vitro tests for cellular immunity in a geographical area in which AIDS has not yet been encountered despite the exclusive use of concentrates manufactured from American sources of plasma. Some patients showed the following abnormalities: lymphopenia (4%), decreased T-helper/T-suppressor (Th/Ts) cell ratios (49%), or both abnormalities (2%). Low Th/Ts were mostly due to absolute or, less frequently, relative increases in Ts cells. The prevalence rates for these abnormalities were the same in patients treated with factor VIII or factor IX concentrates. There was an association between the higher Ts and lower Th cells counts and the low Th/Ts ratios and greater annual consumption of factor VIII and factor IX concentrates. These results support the view that protein load might be an important pathogenetic factor in lymphocyte abnormalities in symptom-free hemophiliacs.     

The use of continuous infusion of factor concentrates in the treatment of hemophilia

Bolus infusion of clotting factor concentrates remains the most common approach to the treatment or prevention of bleeding in patients with hemophilia. Although successful use of continuous infusion of such concentrates has been reported by several groups, this alternative treatment method has not achieved widespread popularity. We report here our experience in one hemophilia center with the use of continuous infusion of factor VIII and factor IX concentrates in 13 patients, 11 with hemophilia A, and 2 with hemophilia B. All patients were treated successfully for bleeding episodes (e.g., hemarthroses, intracranial, or gastrointestinal bleeding) or for surgical procedures (appendectomy, thoracotomy, etc.). Three patients with low titer factor VIII inhibitors were treated successfully with constant infusion therapy, requiring a mean dose of factor VIII concentrate 2.3 fold (8.20 u/kg/h) higher than that of the patients without inhibitors (3.63 u/kg/h) to maintain a circulating plasma level of factor VIII of 1 u/ml. The use of constant infusion of clotting factor concentrates is safe, efficacious, and more convenient than bolus therapy of factor concentrates and should be considered for hospitalized hemophilia patients requiring replacement therapy.     

Treatment type and amount influenced human immunodeficiency virus seroprevalence of patients with congenital bleeding disorders

Two hundred and eighty-two patients with congenital bleeding disorders received blood component replacement therapy between January 1979 and April 1985, were followed-up by the Puget Sound Blood Center's Hemophilia Care Program, and were tested for antibody to human immunodeficiency virus (HIV). Serologic results were obtained at least 1 year after the last exposure to volunteer donor products that were prepared before donor HIV screening or after the last exposure to concentrates produced before the manufacturer's use of treatment methods for inactivation of HIV. In all, 106 patients were anti-HIV positive. The risk of HIV infection was greater in patients with more severe bleeding tendencies, greater exposure to components, and exposure to lyophilized concentrates from large pools of donors. Of 100 patients with hemophilia A who only received cryoprecipitate from volunteer donors from Washington State (during the 6.3-year period), 14% had become anti-HIV positive. Of 27 patients receiving mostly cryoprecipitate but also being exposed to a single lot of concentrate during the same period, 13 (48%) were positive. Of 49 patients treated predominantly or solely with factor VIII concentrates during this period, 43 (88%) were anti-HIV positive. Of 29 patients with von Willebrand disease, four were anti-HIV positive, including 2 of 26 receiving only cryoprecipitate and two of three who had received a single dose of factor VIII concentrate. Of 19 patients who were treated solely with volunteer donor plasma, all remained anti-HIV negative. Of 47 patients exposed to factor IX concentrate, 28 (60%) were positive. Data relevant to the risk of HIV transmission subsequent to screening of the volunteer donor population were also obtained. Treatment records of 55 hemophilia A patients who have remained anti-HIV negative through at least June 1990 showed exposure to 71,173 screened donors from May 1985 through December 1989, and all 55 patients have remained anti-HIV negative.     

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.     

Coagulation factor concentrate in the treatment of the haemorrhagic diathesis of fulminant hepatic failure

To assess the value of clotting factor concentrate infusions in fulminant hepatic failure, a controlled trial was performed in which nine patients were randomly allocated to treatment with either concentrate alone or concentrate plus heparin. The five patients receiving concentrate alone all died, with major bleeding as the direct cause of death in three, whereas in the four receiving heparin as well there was only one instance of bleeding and one patient survived. Clinical evidence of intravascular coagulation appeared in two patients treated with concentrate alone and the laboratory evidence of this progressed during the period of infusions in all patients in both treatment groups, although to a lesser extent in those receiving heparin. Additional evidence for intravascular coagulation came from the changes observed in factor VIII levels which, although initially high in all patients, fell subsequently, particularly in those given concentrate alone.There was some improvement in the prothrombin ratio in both groups of patients but not complete correction, and serial assays of clotting factors showed that although factor II rose to high levels during treatment, factors IX and X showed little response. Thus, the use of concentrate of factor IX in this trial, as well as potentiating intravascular coagulation, was inadequate as replacement for the clotting factor deficiencies.     

Cost-effectiveness in establishing hemophilia carrier detection and prenatal diagnosis services in a developing country with limited health resources

The cost-effectiveness of carrier detection and prenatal diagnosis for hemophilia at the International Hemophilia Training Center, Bangkok, Thailand was studied. From 1991 to 2002, 209 females from 124 families with hemophilia A and B were included. There were 180 hemophilia A carriers and 29 hemophilia B carriers which could be classified into 78 obligate and 131 possible carriers. The phenotypic analysis for possible carriers involved the determination of levels of factor VIII or IX clotting activity (FVIII:C, FIX:C) and the ratio of FVIII:C and von Willebrand factor antigen. The result revealed that 49 females (37.4%) were diagnosed as carriers, 65 females (49.6%) were normal and 17 females (13%) were undetermined. Additional genotypic analysis was provided to 46 families with 74 females with obligate, proven or undetermined carriers within the reproductive life. The polymorphisms associated with factor VIII and IX genes were used including Bcl I for the factor VIII gene and combined use of Mse I, Sal I, Nru I, Hha I and Dde I for the factor IX gene. The informative rate was 59.4% (44/74). Consequently, 12 prenatal diagnoses for fetus at risk were performed. Sex determination was initially determined and followed by the diagnosis of hemophilia through informative gene tracking and/or the measurement of fetal levels of FVIII:C or FIX:C. The result revealed that 3 male fetuses were affected. The total cost of carrier detection and prenatal diagnosis that the families had to pay in the government hospital was 238,600 Baht (US dollars 5,965). It was compared to the estimated cost of minimal replacement therapy using lyophilized cryoprecipitate for the survival time of 30 years in one patient with hemophilia of 1,012,500 Baht (US dollars 25,312.5). The cost of prevention was much less than the replacement therapy. In conclusion, it is cost-effective to establish the service for carrier detection and prenatal diagnosis for hemophilia especially in developing countries with limited health resources.     

Effect of danazol on clotting factor levels, bleeding incidence, factor infusion requirements, and immune parameters in hemophilia

Several recent studies have reported conflicting results on the effectiveness of danazol, an attenuated androgen, in raising plasma levels of clotting factors VIII and IX in patients with hemophilia. We undertook a randomized, double-blind cross-over trial using 8 weeks' administration of danazol (D), 600 mg/d, and 8 weeks' administration of placebo (P) separated by 2 weeks of rest in 12 patients with hemophilia A and four patients with hemophilia B. Plasma factor VIII and IX levels, frequency and type of bleeding episodes, amount of factor concentrate infused, fibrinogen, fibrinolysis assays, antithrombin III, liver function, and immune parameters were followed. During the danazol phase a minimal increase was noted in the average clotting factor levels, an increase that, although statistically significant, was of hemostatically marginal magnitude. Significant increases in protein C and plasminogen levels, however, were observed during the danazol period, suggestive of danazol-mediated enhanced fibrinolysis. Clinically, bleeding frequency was significantly increased, and more clotting factor was consumed during the danazol period. Furthermore, eight episodes of hematuria and oral mucosal bleeding was reported during the danazol phase in contrast to only one episode of hematuria during the placebo phase, consistent with an enhancement of fibrinolytic activity with danazol. We conclude that danazol does not have a hemostatically significant effect on plasma levels of factor VIII and IX but may be associated with enhancement of fibrinolytic activity, resulting in increased bleeding frequency and requiring more clotting factor infusions. Therefore, danazol is not a viable alternative in the treatment of hemophilia.     

Hepatitis C infection in children with hemophilia A and B.

Antibodies to hepatitis C virus (anti-HCV) were quantitated in stored sera from selected groups of hemophilic children (less than or equal to 18 years of age). During the period 1987 to 1989, seropositivity rates were as follows: untransfused hemophiliacs 0% (0 of 11 cases), hemophiliacs treated exclusively with vapor-heated factor VIII or IX concentrates 0% (0 of 9 cases), hemophiliacs treated only with cryoprecipitate or single donor blood products 0% (0 of 9 cases), and hemophiliacs regularly treated with unheated or dry heat-treated factor VIII or IX concentrates 95% (21 of 22 cases). Corresponding alanine aminotransferase (ALT) results were similar: values were always below the upper limit of laboratory normal (40 U/L) in untransfused hemophiliacs, hemophiliacs treated with vapor-heated factor concentrates, or those who received only cryoprecipitate or single donor blood products. By contrast ALT values were greater than 40 U/L in 82% (18 of 22 cases) of hemophilic children regularly infused with unheated or dry heat-treated factor concentrates. Three conclusions are drawn from this data: (1) HCV is a major cause of chronic hepatitis in multitransfused hemophilic children, (2) unheated and dry heat-treated clotting factor concentrates carry a very high risk of transmitting HCV infection, and (3) clotting factor concentrates inactivated by vapor heating carry a very low and perhaps zero risk of transmitting HCV infection. These findings are of therapeutic significance for previously untransfused hemophiliacs susceptible to HCV infection.     

Current status and future prospects for the prophylactic management of hemophilia patients with inhibitor antibodies

Inhibitor antibodies to factor VIII arise in a substantial minority of patients with hemophilia A treated with replacement therapy; factor IX inhibitors in treated hemophilia B patients are considerably less common. As replacement therapy is not feasible in most such patients, hemostasis can generally only be achieved with “inhibitor bypassing agents”, namely (activated) prothrombin complex concentrates and recombinant factor VIIa. These agents are widely used to treat active bleeding in inhibitor patients but they have been used relatively infrequently as prophylactic agents to prevent bleeding and its consequences, mainly progressive joint damage. This is in contrast to hemophilia patients without inhibitors, in whom prophylactic replacement with concentrates of factor VIII or IX has become widely accepted as the optimal strategy to prevent these adverse outcomes. This review addresses the current experience and evidence and the future prospects regarding prophylaxis in inhibitor patients.     

Comparative efficacy of nonheated and heat-treated factor IX complex concentrate in treatment of hemophiliacs with inhibitors

To determine if heat-treated factor IX complex concentrate is as effective as nonheated factor IX complex concentrate for treatment of subjects with hemophilia A and antifactor VIII antibodies (inhibitor patients), we have retrospectively reviewed consecutive home treatment records of ten inhibitor patients who had been receiving nonheat-treated factor IX complex concentrate (NHT-Konyne) and subsequently converted to heat-treated factor complex concentrate (Konyne-HT) when it was licensed in late 1984. Overall, 162 of 284 (57%) separate bleeding episodes treated with NHT-Konyne and 53 of 80 (66.3%) separate bleeding episodes treated with Konyne-HT required only one treatment course of approximately 60-75 U/kg. The distribution of bleeding sites and the absolute factor IX unitage required per treatment episode were similar for both preparations. These data suggest that the percentage of hemophilic inhibitor patients responding to factor IX complex concentrate remains at least 50%, as was reported several years ago in a controlled study, and that inhibitor bypass activity has not altered by heat treatment.     

Adeno-associated virus-mediated gene transfer for hemophilia B

Hemophilia is the bleeding diathesis caused by mutations in the gene encoding factor VIII (hemophilia A) or factor IX (hemophilia B). Currently, the disease is treated by intravenous infusion of the missing purified clotting factor. The goal of gene transfer for treating hemophilia is to achieve sustained expression of factor VIII or factor IX at levels high enough to improve the symptoms of the disease. Hemophilia has proven to be an attractive model for those interested in gene transfer, and multiple gene-transfer strategies are currently being investigated for the hemophilias. The most promising preclinical studies have been with adeno-associated viral vectors (AAV); introduction of AAV vectors expressing factor IX into skeletal muscle or liver in hemophilic dogs has resulted in the long-term expression of factor IX at levels that are adequate to improve disease symptoms. Efforts to translate these findings into the clinical arena have proceeded slowly because of the lack of prior clinical experience with parenteral administration of AAV. In a staged approach, AAV-factor IX (AAV-F.IX) was first administered at doses of up to 1.8 x 10(12) vector genomes/kg (vg/kg) into the skeletal muscles of men with hemophilia B. This trial established the safety of parenteral administration and also showed that general characteristics of AAV transduction were similar in mice, dogs, and humans. In an ongoing trial, AAV-F.IX is being administered into the hepatic circulation of men with severe hemophilia B. The goal of these studies is to identify a safe dose that reliably yields circulating levels of factor IX >2% of normal levels in all subjects. This goal has already been achieved in the hemophilia B dog model; the ongoing study will determine whether a similar result can be achieved in humans with hemophilia B.     

Decreased helper/suppressor cell ratios after treatment with factor VIII and IX concentrates and fresh frozen plasma

The immunologic status of three groups of multiply transfused asymptomatic patients was evaluated. These included five with acquired inhibitors to factor VIII treated with both factor VIII and factor IX concentrates (Group A), seven with hemophilia B treated with factor IX concentrate (Group B), and six with hemophilia B treated with fresh frozen plasma (Group C). Mean helper/suppressor T cell ratios (± SEM) for the three groups were 0.72 ± 0.09, 1.35 ± 0.18, and 1.37 ± 0.12, respectively. All three differed significantly (p < 0.01) from the control mean ratio of 2.22 ± 0.16. In addition, the mean ratio of Group A patients was significantly different (p < 0.01) from those of Groups B and C. An inverted ratio (less than 1.00) was found in all Group A patients and only one Group B patient. Increased IgG levels were found in 80, 57, and 50 percent of each group, respectively. These immunologic findings bear a striking resemblance to those of the acquired immunodeficiency syndrome (AIDS) of homosexuals, intravenous-drug abusers, Haitian immigrants, and factor VIII concentrate-treated hemophiliacs. Transmission via a blood-borne infectious agent seems likely.     

Clinical analysis of 4 Chinese hemophiliacs with human immunodeficiency virus infection

Human immunodeficiency virus (HIV-is) now considered the causative agent of acquired immunodeficiency syndrome(AIDS). A high risk of AIDS has been reported among patients with hemophilia who received lyophilized commercial factor VIII and IX concentrates of American origin. In a prevalence survey conducted from September to December 1985, HIV antibodies were found in all the 4 patients with hemophilia treated with the batch number W87307, 955 I.U. of American commercial factor VIII concentrate supplied by Armour pharmaceutical Company U.S.A. One of the seropositive patients developed AIDS-related complex (ARC) and died of cerebral hemorrhage. The other three sero-positive patients had abnormalities in cell mediated immunity; among them two developed left lumbosacral radiculopathy and hemorrhagic herpes zoster and one remains well so far.     

Liver dysfunction in Pennsylvania's multitransfused hemophiliacs

Transaminase values [alanine amino transferase (ALT) and aspartate amino transferase (AST)] and markers for hepatitis B were serially determined in 558 hemophiliacs exposed to blood products. Hepatitis B surface antigen (HB_sAg) persistent for over 12 months was present in 6% of the patients. Antibody to hepatitis B surface antigen (anti-HBs) was noted in 90% of the 259 patients treated with factor VIII or IX concentrates but in only 49% of the 43 patients treated with fresh frozen plasma (FFP) or cryoprecipitate. Persistently abnormal transaminase values were noted in 31% of the patients treated with commercial concentrates but in only one (2%) of the patients exposed to cryoprecipitate or FFP. This difference continued even when the two groups of patients were matched for the amount of blood products, up to 50, 000 units, which they had received in the study period. In the concentrate-treated patients, no correlation could be found between transaminase values and the number of units of factor VIII or IX they had received during the six years of the study (1973–1978).Supported in part by the Pennsylvania Hemophilia Centers and the Pennsylvania State-Wide Hemophilia Program.     

Dominant inheritance of hemophilia A in three generations of women.

A bleeding diathesis is described which is phenotypically indistinguishable from hemophilia A and which has been transmitted as a dominant trait in three generations of women in a North Carolina kindred. The abnormal phenotype is characterized by clinical mildness and slightly abnormal clotting time, prothrombin consumption, and partial thromboplastin time. Bleeding time, platelet count, clot retraction, tourniquet test, and prothrombin time are normal. Concentration of factors I, II, V, VII, IX, X, and XII are normal, while factor VIII activity is reduced to 2%-5% of control values. De novo synthesis of factor VIII does not occur after transfusion; factor VIII-related antigen is normal; patients' plasmas aggregate platelets normally in the presence of ristocetin, and a typical protein pattern is seen when a chymotryptic digest of cryoprecipitate of the proband is examined by SDS-polyacrylamide gel electrophoresis. Six possible genetic explanations are entertained. Balanced X-autosomal translocation of hemophilia A heterozygotes has been excluded by cytogenetic analysis of metaphase chromosomes. Classes von Willebrand's disease (vWd) is probably excluded on the basis of the laboratory data, and extreme lyonization of hemophilia A heterozygotes on probabilistic grounds. The genetic possibilities which cannot be excluded include a previously unrecognized variant mutation at the vWd locus, a dominant mutation at the hemophilia A locus on the X chromosome, and dominant mutation at a hypothetical fourth locus involved in factor VIII synthesis and control.     

Management of haemophilia in patients with high-titre inhibitors: focus on the evolution of activated prothrombin complex concentrate AUTOPLEX® T

Numerous therapeutic strategies have been applied to the management of patients with inhibitors to factors VIII or IX. Different treatment approaches are analysed including prothrombin complex concentrates (PCCs), activated prothrombin complex concentrates (aPCCs), porcine factor VIII concentrate, inhibitor neutralization, immune tolerance therapy, immunosuppressive regimens and recombinant factor VIIa. Clinical data are reported in the analysis of several treatments. PCCs and aPCCs have gained widespread acceptance as the standard first-line approach for patients with inhibitors. The aPCC AUTOPLEX® T has achieved a high response rate with a low level of thrombotic events. Four case studies are presented in which AUTOPLEX® T has been used successfully. Administration of platelet concentrate or, in elective surgery, waiting for inhibitor levels to decline are useful adjuncts to some treatments. The optimal treatment depends on the patient's inhibitor status – low responder (minimal or no increase in inhibitor levels upon administration of replacement clotting factor) or high responder (replacement clotting factor generates inhibitor production). A suggested algorithm for treating high-responder inhibitor patients is presented.     

Head trauma in hemophilia. A prospective study

Intracranial hemorrhage (ICH) remains a serious problem in hemophilia. Consecutive episodes of ICH or reports of head trauma were prospectively recorded in 140 patients with hemophilia seen during a two-year period. Forty of 48 consecutive episodes of ICH or trauma occurred in 37 patients with severe disease (less than 1% factor VIII or IX). Five injured patients had inhibitors to factor VIII. Two fatalities occurred following injury and one patient died following a spontaneous bleed. Injury in 40 instances warranted replacement therapy. No patient given coagulation factor within six hours of injury experienced ICH. The risk of ICH following head trauma (13% in this series) warrants aggressive use of coagulation factor replacement. Watchfulness in dealing with such patients and early therapy may be more necessary than often realized.     

Human T cell leukemia virus type III antibody, lymphadenopathy, and acquired immune deficiency syndrome in hemophiliac subjects. Results of a prospective study

A cohort of 63 hemophiliac subjects was followed for clinical and immunologic abnormalities related to the acquired immune deficiency syndrome (AIDS). When evaluated in early 1984, antibody to human T cell leukemia virus type III (HTLV-III) was detected in the serum of 59 percent (24 of 41) of factor VIII or IX concentrate recipients, but in none (0 of six) of the cryoprecipitate/fresh frozen plasma recipients. HTLV-III-seropositive hemophiliac subjects, on average, had been exposed to twice as much concentrate during the previous year as seronegative hemophiliac subjects. The seropositive group had a significantly lower mean helper/suppressor T cell ratio and absolute helper T cell level than the seronegative group. By early 1984, 13 hemophiliac subjects in the study population had lymphadenopathy and one had AIDS. Antibody to HTLV-III was detected in the serum of 13 of these 14 hemophiliac subjects with overt clinical disease. The prevalence of lymphadenopathy or AIDS among HTLV-III-seropositive hemophiliac subjects was 54 percent (13 of 24). It is concluded that HTLV-III antibody occurs with high frequency in hemophiliac subjects, and is related to the amount of factor VIII or IX concentrate infused. Over half of HTLV-III-seropositive hemophiliac subjects in this population had overt clinical disease with either lymphadenopathy or AIDS.