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We designed a lentiviral vector expressing a chimeric antigen receptor with specificity for the B-cell antigen CD19, coupled with CD137 (a costimulatory receptor in T cells [4-1BB]) and CD3-zeta (a signal-transduction component of the T-cell antigen receptor) signaling domains. A low dose (approximately 1.5×10(5) cells per kilogram of body weight) of autologous chimeric antigen receptor-modified T cells reinfused into a patient with refractory chronic lymphocytic leukemia (CLL) expanded to a level that was more than 1000 times as high as the initial engraftment level in vivo, with delayed development of the tumor lysis syndrome and with complete remission. Apart from the tumor lysis syndrome, the only other grade 3/4 toxic effect related to chimeric antigen receptor T cells was lymphopenia. Engineered cells persisted at high levels for 6 months in the blood and bone marrow and continued to express the chimeric antigen receptor. A specific immune response was detected in the bone marrow, accompanied by loss of normal B cells and leukemia cells that express CD19. Remission was ongoing 10 months after treatment. Hypogammaglobulinemia was an expected chronic toxic effect.

In a double-blind study, we randomly assigned 84 patients with chronic lymphocytic leukemia who were judged to be at increased risk of bacterial infection to receive intravenous immunoglobulin G (400 mg per kilogram of body weight) or a placebo every three weeks for one year. Eligible patients had hypogammaglobulinemia, a history of infection, or both. The patients receiving immunoglobulin had significantly fewer bacterial infections during the study period than those receiving placebo (23 vs. 42; P = 0.01). This reduction was most striking in the patients who completed a full year of treatment (14 vs. 36; P = 0.001). The period from study entry to the first serious bacterial infection was significantly longer in the patients receiving immunoglobulin (P = 0.026). There was no significant difference between the two groups in the incidence of nonbacterial infection. Immunoglobulin therapy was tolerated well; there were no serious adverse reactions, and the incidence of minor reactions was low. We conclude that selected patients with chronic lymphocytic leukemia who are at risk of bacterial infection can be substantially protected from this complication by the regular intravenous administration of immunoglobulin.

We investigated suppressor and helper T cells in 19 patients with variable immunodeficiency to assess the possibility that defective interactions among these cells and B lymphocytes are the chief cause of the inadequate plasma-cell development and hypogammaglobulinemia characterizing these syndromes. We accomplished functional separation of the two T-cell subsets, using irradiation, which selectively inactivates T-cell suppressors. The patient B lymphocytes were usually capable of some differentiation into plasma cells when co-cultured with T cells manipulated to optimize helper effects. Eighteen of 19 patients showed quantitatively poor plasma-cell production even under these conditions. However, only one had defective enough helper function, and only one sufficiently excessive suppressor activity for these factors to be considered the major pathogenetic process in each case. Since neither an absolute defect in B cells nor consistent abnormalities in modulator T cells were demonstrable in most patients, other explanations must be sought for the mechanisms underlying this form of primary immune deficiency.

Three males in one family (two siblings and one maternal cousin) had an illness with cervical adenopathy, hepatosplenomegaly, and a fulminant febrile course. In the two survivors agammaglobulinemia developed. One of them became ill at the age of six months and had an Epstein-Barr-virus antibody titer of 1:10 during illness and convalescence. The white-cell count was 120,000 with 90 per cent lymphocytes, most being atypical and forming increased numbers of sheep erythrocyte rosettes. IgM was elevated, IgA normal and IgG decreased. Subsequently, all immunoglobulins were absent, and the Epstein-Barr-virus antibody titer became negative. Peripheral B-cell number remained normal, but abnormal lymph-node architecture associated with failure to respond to antigenic challenge indicated B-cell dysfunction. The pathogenesis of this entity may involve an abnormal T-cell response to transformation of B cells by Epstein-Barr virus, leading to B-cell dysfunction and agammaglobulinemia.