T cell depletion with anti-CD5 immunotoxin in histocompatible bone marrow transplantation. The correlation between residual CD5 negative T cells and subsequent graft-versus-host disease.

Twenty-nine patients with advanced leukemias (median age 34 years) received histocompatible sibling marrow that had been depleted of T cells by ex vivo incubation with anti-CD5 monoclonal antibody-ricin immunotoxin (T101-R) for the purpose of graft-versus-host disease prophylaxis. Donor cell engraftment was documented in 28/29 patients by DNA restriction fragment length polymorphisms. In this pilot study the dose of T101-R incubated with donor marrow was increased in a stepwise manner from 300 ng (10 patients) to 600 ng (5 patients) to 1000 ng immunotoxin (IT)/10(7) bone marrow mononuclear cells (14 patients) in an attempt to achieve more effective GvHD prophylaxis. A statistically significant reduction in acute GvHD was achieved for patients receiving marrow pretreated with 1000 ng of immunotoxin (34%) compared to recipients of BM treated with 300 ng immunotoxin (100%, P = 0.0004). T-depleted marrow samples were evaluated for residual T cell activity using several in vitro assays including proliferation to the purified mitogen PHA (HA-17) and in mixed lymphocyte culture (MLC), T cell cytotoxicity, a limiting dilution assay for detecting precursors of proliferating T cells (LDApPTL), and phenotypic analysis of viable T cells expanded in 16-day culture with interleukin 2. The extent of T cell depletion determined by LDA assay varied widely at each immunotoxin concentration used. Thus, there was no correlation between the dose of T cells infused and subsequent GvHD. Phenotyping of lymphocytes recovered from immunotoxin-treated marrow demonstrated that residual T cells were CD5 negative in all cases tested. The only in vitro parameter that predicted subsequent acute or chronic GvHD was the demonstration of viable CD5 negative lymphocytes with T cell phenotype (CD2, CD3, and/or CD7 positive) after 16-day culture with IL-2 of the T-depleted bone marrow. We observed that such CD5 negative cells expressing other T cell markers have cytotoxic function and speculate that these cells may be capable of mediating GvHD in allogeneic transplantation.     

Plasma pharmacokinetics of high-dose oral busulfan in children and adults undergoing bone marrow transplantation

Abstract: We have analyzed the plasma pharmacokinetics of busulfan in 272 patients receiving high-dose oral busulfan and intravenous cyclophosphamide in conjunction with allogeneic or autologous bone marrow transplantation. The patients ranged in age from 2 months to 59 yr (mean 10, median 12 yr) and had the following diagnoses: thalassemia or sickle cell anemia (n = 74); leukemia or myelodysplasia (n = 112); inborn errors of metabolism (n = 41) or immunodeficiency (n = 45). Plasma specimens were collected following the first dose for each patient which ranged from 1 to 4 mg/kg (mean ± SD, 1.21 ± 0.41, median 1.15). Busulfan was quantitated using ultraviolet absorbance detection after derivatization and HPLC separation. Pharmacokinetic parameters were derived by modeling the raw data to fit first-order single compartment kinetics. The kinetic parameters showed wide interpatient variability independent of age and diagnosis. There was a statistically significant correlation of age with the following parameters: area under the curve (AUC); maximal concentration; minimum concentration; clearance; volume of distribution and absorption half-time. The coefficients of determination (i.e. correlation coefficient squared) were low ranging from 0.04 to 0.12 implying only a small part (i.e. 4–12%) of the variance was explained by age. Although busulfan pharmacokinetics are age-related most of the variability is not explained by age or diagnosis.     

Diminished neo-antigen response to keyhole limpet hemocyanin (KLH) vaccines in patients after treatment with chemotherapy or hematopoietic cell transplantation

Relapse is the most common cause of treatment failure for advanced cancer, even those treated with autologous hematopoietic cell transplantation (HCT). Effective tumor-specific immunotherapy may decrease relapse, however, this will fail if the immune system is unable to respond. We developed a strategy to test immune responses with a single injection of the bona fide neo-antigen KLH. The model was first tested in 37 normal volunteers using three KLH vaccines: Intracel KLH, Biosyn KLH, and Biosyn KLH + adjuvant. Despite finding the immunogenic epitope conserved in both products, intact Intracel KLH induced a better response compared to a purified 350/390 kDA subunit of KLH contained in the Biosyn KLH product. Addition of a synthetic oil adjuvant (Montanide ISA51) restored the response to a single injection of Biosyn KLH. A quantitative readout measured by a KLH-specific cellular and humoral response with isotype switching 1 month after KLH vaccination was established. To test the integrity of the adaptive immune response in cancer patients, we vaccinated 14 patients post-HCT and 19 patients with advanced cancer with KLH vaccines that elicited a 100% response rate in normal volunteers. In marked contrast to normal subjects, both responses were significantly impaired up to 16 months after autologous HCT with an intermediate response in advanced cancer patients. KLH vaccines are safe and require only a single injection to test neo-antigen responses providing an optimal platform for definitive testing of strategies to improve diminished immune recovery after chemotherapy or post-HCT.     

Human surfactant protein a suppresses T cell-dependent inflammation and attenuates the manifestations of idiopathic pneumonia syndrome in mice

We have previously shown an association between growth factor-induced upregulation of surfactant protein (SP)-A and suppression of alveolar inflammation in our murine model of donor T cell-dependent lung dysfunction after bone-marrow transplantation, referred to as idiopathic pneumonia syndrome (IPS). We hypothesized that SP-A protects the lung in vivo from IPS injury by downregulation of alveolar inflammation. Human SP-A (100 microg), purified by n-butanol extraction or preparative isoelectric focusing, was transtracheally instilled on Day 4 after BMT during a time of in vivo donor T-cell activation. At 48 h after treatment, immunohistochemical staining of lung sections showed that SP-A did not alter T cell- dependent cellular infiltration. However, macrophages from SP-A-instilled mice were less injured and spontaneously produced less tumor necrosis factor-alpha than did cells from buffer-instilled mice. Although exogenous SP-A did not significantly alter bronchoalveolar lavage fluid (BALF) high levels of total protein (TP), an inverse correlation between BALF SP-A and TP concentrations (r = -0.65; P = 0.02) was observed in SP-A-treated but not in buffer-instilled mice. The only difference between the effects of the two sources of SP-A was that butanol-extracted SP-A, but not isoelectric focusing-purified SP-A, suppressed the interferon-gamma/nitric oxide pathway. We conclude that SP-A downregulates T cell-dependent alveolar inflammation by multiple pathways leading to decreased IPS injury.