Transfusion Safety Study (TSS)

BACKGROUND:

In the summer of 1981, the Centers for Disease Control (CDC) alerted the medical community to an unexpected outbreak of Pneumocystis carinii pneumonia and Kaposi's sarcoma in young homosexual men, individuals not known to be at risk for these uncommon diseases. Studies of immunologic functions in these patients demonstrated lymphopenia, cutaneous anergy, reduced helper T-lymphocyte (T4) subpopulations, depressed ratios of helper T-lymphocytes to suppressor T-lymphocytes (T4:T8), abnormal lymphocyte responses to mitogen stimulation, decreased natural killer-cell activity, and often hypergammaglobulinemia. The name of acquired immunodeficiency syndrome (AIDS) was given to this disorder of immunologic regulation with opportunistic infections or Kaposi's sarcoma or both.

Since that time, AIDS was reported in patients with hemophilia and in others receiving blood transfusions. The NHLBI was delegated responsibility for studies to elucidate, through a systematic prospective study, the possible association of blood product use with AIDS. The incidence of transfusion-acquired AIDS was so low as to preclude a general prospective study of transfusion recipients to determine the overall incidence of the disease. By focusing on patient groups that appeared to have a higher likelihood for developing AIDS because they required chronic, repeated transfusion therapy, information about the epidemiology of the disorder could be more readily obtained. Continuing medical evaluation of these patients from apparent high-risk groups in a prospective fashion allowed identification of significant emerging physiologic alterations and to follow the time-course of pathologic developments.

The purpose of this study was to develop a clear picture of what immunologic changes occurred in patients who were transfused and to determine when these changes occurred and how long they lasted. Since most of the patient population was heavily transfused, some of the study subjects eventually developed AIDS. Information obtained during the study about these patients was then used to answer such questions as: Which factors determined a particular person's risk of developing AIDS and to what degree? What alterations occurred before the clinical manifestations of AIDS? Was progression from normal to defective cell-mediated immunity to AIDS strictly unidirectional or did altered cell-mediated immunity in the study cohort ever regress to normality? If progression was not unidirectional, what determined the outcome? Also, the importance of establishing a serum and cell repository could not be overemphasized, since, as new scientific information became available, these specimens enabled the performance of a number of different retrospective studies.

In 1984 a serum repository for HIV testing was established. The task of the repository was to collect and store serum samples from blood donors in four blood transfusion units located in four major risk areas for AIDS, namely New York, San Francisco, Miami, and Los Angeles. Blood was obtained from the New York Blood Center in New York City, the Irwin Memorial Blood Bank in San Francisco, the Red Cross in Los Angeles, and the American Red Cross, South Florida Region, in Miami. The purpose of the repository was to determine the outcome of the transfusion of blood components retrospectively found to show HIV infection of the donor. The collected sera were separated, indexed, frozen, and stored.

In 1984 the second part of the Transfusion Safety Study, the prospective study, was initiated by NHLBI under a separate request for proposal. The testing of the 201,000 serum specimens in the donor repository for antibody to HIV was carried out by laboratories in the prospective study. Those donors confirmed to be anti-HIV positive and matching donors confirmed to be anti-HIV negative were recruited as TSS subjects. Recipients of blood from the positive donors and the negative donors were also recruited as subjects.

In September 1984, the TSS began a nine month planning phase during which the protocols and data systems for the prospective study were developed. Subjects were entered in July 1985 through June 1989. Analysis continued through November 1997. There were clinical centers in Los Angeles, San Francisco, New York City, and Miami. The coordinating center was at the University of Southern California. The central laboratories including the immunological standardization laboratory, the immunological reagents laboratory, and the central processing laboratory were located in Los Angeles, with one of the immunology laboratories located in Seattle, Washington at the Puget Sound Blood Center.

DESIGN NARRATIVE:

At baseline, each subject received a physical examination, was questioned as to medical history, and gave blood samples for immunologic and other studies. Each subject returned at a specified interval for a repeat of studies specified in the protocol. Blood studies included complete blood cell count, characterization of immunologic cells such as T- and B-lymphocytes and natural killer-cells. Plasma and Buffy coat cell suspensions were stored frozen. Alanine aminotransferase levels were determined. Serologic tests were performed for hepatitis, Epstein-Barr virus, and cytomegalovirus. Markers of immune status, including immune globulin levels were measured. The study ended in November, 1997.