Douglas M. Strong

Heterogeneity of T-CLL defined by monoclonal antibodies in nine patients

Abstract Surface markers were examined on peripheral lymphocytes from 450 patients with chronic lymphocytic leukemia (CLL). In nine (2%), the lymphocytes had the characteristics of thymus-derived cells (T-CLL). These nine patients had a milder clinical course than that usually attributed to T-CLL, lack of massive hepato- or splenomegaly, and fewer skin lesions. Lymphocytes from these patients were studied with surface markers, including a panel of monoclonal antibodies (MoAb) and also for in vitro functional activity. Whereas cells from two patients appear to represent heterogeneous proliferations, as detected by MoAb, seven cases gave a clearly recognized phenotype. Evaluation of immunoregulatory functions showed that OKT8 + , Fc IgG receptor-positive cells (three patients) were able to suppress either lymphocyte proliferation, or immunoglobulin biosynthesis, or both. In three patients with a proliferation of OKT4 + cells, in vitro help was not demonstrable, but in two of them, high levels of serum IgA were detected. Our results clearly show that T-CLL may originate from different T-cell subpopulations. Some, if not all of the T-CLL cells, seem to represent the proliferation of well-differentiated T cells, corresponding to the normal T-cell subsets. In some cases these cells retain functional activity. The expression of a given phenotype pattern, as detected by MoAb, represents a useful tool in determining the clonal origin of proliferating cells.

Lyophilized veins as arterial interposition allografts

Abstract Venous allografts were evaluated in two models. Lyophilized allograft veins used as interposition grafts in the infrarenal aorta of the canine were studied and found to be patent at 1 year. Pathologic examination of the grafts revealed mild intimal hyperplasia and persistence of the basic structure of the lyophilized vessel. The ability of venous tissue to elicit an antibody response when transplanted into an allogeneic recipient was studied in the rat using the lymphocyte cytotoxicity assay. Fresh and Me2SO-cryoprotected frozen veins produced circulating antibody when used as interposition grafts in the infrarenal aorta of the rat. Lyophilized and noncryoprotected frozen veins did not induce measurable antibody. Lyophilized allograft veins are a nonimmunogenic vascular graft material with acceptable long-term patency.

Determination of surface immunoglobulin density on frozen-thawed mononuclear cells analyzed by the fluorescence-activated cell sorter☆

Abstract Recent data have demonstrated that differences in sIg density on B lymphocytes distinguish functionally distinct subpopulations of these cells. Other reports suggest that cyropreservation may change the frequency of sIg-bearing lymphocytes. To determine if cryopreservation alters either the frequency of sIg cells or the distribution of sIg density, PBM from normals and patients with CLL and LCL were analyzed using the FACS. Aliquots of Ficoll-Hypaque-separated PBM were controlled-rate frozen (1 °C/min) in 7.5% Me 2 SO in RPMI 1640 and thawed in a 37 °C water bath on the same day. Fresh and frozen-thawed PBM aliquots were labeled with fluorescein conjugates of F(ab′) fragments of affinity chromatography-purified anti-Fab or class-specific anti-μ, anti-δ, anti-γ, or anti-α. Histograms of relative cell fluorescence, reflecting sIg density, were prepared for each aliquot with the FACS. The frequency of sIg-bearing PBM labeled with each reagent was not significantly altered by freezing. Likewise, FACS profiles demonstrated that the distribution of sIg density on normal and CLL PBM was unchanged after freezing. However, the fluorescence peak produced by frozen-thawed unlabeled cells was occasionally slightly broader than that of fresh cells, suggesting increased autofluorescence induced by freezing. These data indicate that frozen cell preparations may be utilized for the study of B-lymphocyte subsets as determined by sIg density.

Hand-mirror variant of acute lymphoblastic leukemia. Evidence for early T-cell lineage in two cases by evaluation with monoclonal antibodies

Lymphoid cells from two patients with hand‐mirror variant of acute lymphoblastic leukemia (ALL) were studied with various monoclonal antibodies in attempts to determine their derivation and differentiation. The predominant feature of the malignant bone marrow cells was strong reactivity with antibody 3A1, which stains the majority of normal T‐cells and is apparently present on all T‐ALL cells. In addition, a less intense binding was observed with antibody 4F2, which reacts with activated or rapidly dividing cells, and antibody 10.2, which reacts with all thymocytes and most peripheral T‐cells. Most other antibodies with a wide variety of specificities were not reactive or, in the case of a few anti‐T‐cell antibodies showed, by fluorescence‐activated cell sorter analysis only weak staining on some cells. Sequential bone marrow studies in one patient, before and during treatment with chemotherapy, revealed a reduction of 3A1‐positive cells, concordant with a decrease of malignant cells in the marrow. When involved lymph nodes, peripheral blood, or marrow were studied, similar reactivity patterns were found in all locations. The data obtained suggest that in both patients with hand‐mirror variant of ALL, the malignant lymphoid cells were immature cells of early T‐lymphocyte lineage. The relation of phenotype by monoclonal antibody analysis to hand‐mirror morphologic type and biologic function is discussed.

Lack of expression on cultured human T-lymphocytes of a T-cell antigen shared by the MOLT-4 cell line and normal human thymocytes.

SummaryFour hematopoietic cell lines (CCRF-CEM, HSB-2, MOLT-4, and RPMI-8402), derived from acute lymphoblastic leukemia and expressing T-cell surface markers (T-HCL), were studied with two specific anti-T-cell sera. The sera were raised in rabbits against human thymocytes (anti-HTY) and against T-cells cultured in the presence of conditioned medium derived from lymphocytes stimulated with PHA (anti-CTC). Both sera were absorbed to obtain a T-cell specific pattern of reaction and were further absorbed with normal peripheral blood lymphocytes or with each of the four T-HCL. The anti-HTY sera absorbed with CEM, 8402, and HSB-2 still reacted with MOLT-4. A similar pattern of reactivity was found only with the anti-CTC absorbed with 8402, whereas, after absorptions with the other cell lines, this antiserum was unreactive against MOLT-4. After absorption with normal peripheral blood lymphocytes, anti-HTY still reacted with thymocytes and MOLT-4 but was negative on CTC. In contrast, anti-CTC absorbed with peripheral blood lymphocytes (PBL) was negative on thymocytes and MOLT-4 but still reacted against CTC. Our data confirm the existence of a T-cell antigen (probably an early T-cell differentiation antigen) shared between thymus and MOLT-4. This antigen is not expressed on CTC, although these cells express an antigenic pattern more complex than PBL. Antisera to CTC represents a source of anti-T-cell sera free of contamination with antibodies to early thymus-related antigens but containing other T-cell-related specificities.