Efficacy of viral clearance methods used in the manufacture of activated prothrombin complex concentrates: focus on AUTOPLEX T.

Various methods are described for the elimination of infectious viruses from activated prothrombin complex concentrates (aPCCs) and for the analysis of the final products (AUTOPLEX T and FEIBA VH). Viruses of concern in human plasma-derived products are enveloped (hepatitis B and C, cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus [HIV]) and nonenveloped (hepatitis A and parvovirus B19). Donated blood used for AUTOPLEX T is screened for antihepatitis C, HBsAg, anti-HIV types 1 and 2, and p24 antigen. Plasma pools utilized for raw materials are also tested by PCR for HIV and hepatitis C virus. Partial virus inactivation and partitioning are achieved by purification of the aPCC. Further reduction of virus infectivity is accomplished by lyophilization and dry-heat treatment. Each step undergoes virus elimination validation studies in which a relevant sample is 'spiked' with the appropriate virus or model virus. The total reduction in virus from raw material to final product can then be calculated. For AUTOPLEX T the cumulative log10 reduction factors for several viruses vary from 4.2 to 14.3. This ensures an exceptionally high margin of safety. Definitive evidence for product safety was obtained by clinical observation of treated patients. The viral inactivation process of AUTOPLEX T involves a four-tier viral safety program, including Cohn alcohol fractionation and dry-heat treatment, in place of the two-stage vapour-heating process for FEIBA.

Genotypic and phenotypic analysis of human immunodeficiency virus type 1 isolates from patients on prolonged stavudine therapy.

Development of stavudine resistance was studied using human immunodeficiency virus type 1 isolates from 13 patients treated with stavudine for 18-22 months. Drug sensitivity testing on 11 of these pre- and posttherapy isolates identified only 2 posttreatment isolates with decreased stavudine sensitivity (ED50s < 4-fold higher than the average pretreatment ED50). Genotypic analysis of all 13 pairs of isolates identified multiple mutations in the reverse transcriptase (RT) gene. However, no genetic basis was identified to account for the observed changes in stavudine susceptibility. A recombinant virus containing the entire RT gene of the posttherapy isolate displaying the greatest resistance remained sensitive to stavudine. Five of the stavudine posttreatment isolates developed resistance (9- to 176-fold) to zidovudine, although the relationship between stavudine treatment and the appearance of zidovudine resistance remains unexplained. Analysis of 10 additional pairs of isolates did not confirm this relationship. The low frequency and modest degree of change in stavudine sensitivity following prolonged treatment is very encouraging.

Natural history and serologic diagnosis of infants born to human immunodeficiency virus-infected women.

Perinatal transmission of human immunodeficiency virus is thought to occur in 25% to 50% of the offspring of infected women. Standard diagnostic methods do not permit identification of the infected newborns. To assess diagnostic methods and document the natural history of perinatal human immunodeficiency virus infection, 20 children born to human immunodeficiency virus-infected women were followed prospectively for 18 months by measuring antibody titer, Western blot profiles, and antigenemia, and the results were compared with clinical outcome. Endogenous synthesis of anti-human immunodeficiency virus IgG was demonstrated in 6 of the 8 infected children. Four children synthesized IgM against human immunodeficiency virus. Five had demonstrable p24 antigenemia. No significant differences between infected and noninfected children were noted at birth except drug withdrawal, which occurred more frequently in noninfected infants. The incidence of adenopathy, hepatomegaly, and neurologic and immunologic abnormalities in the infected children were compared with noninfected children. The distinguishing illnesses were the opportunistic infections, lobar pneumonia, and failure to thrive. Seven of the 8 infected children had human immunodeficiency virus-mediated disease by 1 year of age (Centers for Disease Control [Atlanta, Ga] P2 classification), and four had acquired immunodeficiency syndrome (Centers for Disease Control P2D). These studies offer an approach to diagnosis of human immunodeficiency virus infection in infants and document the natural history and possible outcomes of infected children.

Reevaluation of T cell subset monitoring in cyclosporine-treated renal allograft recipients.

The predictive value of peripheral blood T cell subset monitoring in renal allograft recipients has been questionable, and there has been no information concerning the correlation of T cell subset changes with the clinical event related to cyclosporine nephrotoxicity. This study was conducted to investigate the clinical usefulness of serial T cell subset monitoring in 34 consecutive renal transplant patients treated with cyclosporine by determining the total peripheral lymphocyte count and T cell subset counts using Leu-4, Leu-3ab, and Leu-2a monoclonal antibodies and flow cytometry up to 6 months after transplantation. The absolute counts of all cells were lower in transplanted patients than those of normal controls, but were not different from those of hemodialysis patients. During infection, the helper/suppressor (H/S) ratio and the cell counts, except for suppressor cells, decreased significantly. Within one week prior to rejection, all cell counts also decreased significantly. Furthermore, cell counts before steroid-resistant rejection were significantly lower than those before steroid-responsive rejection. In contrast, lymphocyte and T cell counts were increased significantly within one week prior to cyclosporine nephrotoxicity being diagnosed; the H/S ratio was not correlated with rejection or toxicity. These results indicate that H/S ratio is not associated with clinical events of renal allograft recipients, but serial lymphocyte and T cell subset counts can provide valuable information for the differentiation of rejection from cyclosporine nephrotoxicity, and also for predicting the outcome of the allograft rejection.

Effects of radiation therapy on T-lymphocyte subpopulations in patients with head and neck cancer.

Cellular immunity was assessed in 85 patients with head and neck cancer with monoclonal antibodies to lymphocyte surface antigens that identify total T cells, helper cells, and suppressor cells. The control group consisted of 22 healthy volunteers. Nine patients who had surgical procedures for benign diseases were also studied. Compared with the controls, the patients with cancer who received radiation therapy had a significant decrease in total lymphocytes, T cells, helper cells, suppressor cells, and decreased helper/suppressor cell ratio. Significant decreases in lymphocyte subpopulations were not detected in patients tested before treatment or in patients treated with surgery alone. The immune deficits observed were prolonged in duration, with some present in the patients studied up to 11 years after radiation therapy. This long-lasting immune depression may have relevance to tumor recurrences and second primaries in patients with head and neck cancer treated by radiation therapy and to attempts at increasing cure rates with adjuvant agents that improve immune reactivity.