George Janossy

Acid Esterase in Human Lymphoid Cells and Leukaemic Blasts: a Marker for T Lymphocytes

A non‐specific acid alpha‐naphthyl‐acetate esterase activity was investigated in human lymphoid cell populations from tonsils, blood, thymus and in different leukaemias. Four patterns have emerged. (i) The vast majority of T lymphocytes (peripheral blood, tonsils) showed a localized, intense reaction product (‘T‐like’). (ii) A thymocyte subpopulation expressed faint, localized enzyme activity (‘Thy‐like’) but the majority of thymocytes showed no esterase activity. Some cells from acute lymphoblastic leukaemias with thymocyte surface characteristics had a ‘Thy‐like’appearance. (iii) Most B lymphocytes and cells from chronic lymphocytic leukaemias were esterase negative. No activity was seen in mitogen activated peripheral blood T and B lymphoblasts from peripheral blood and in leukaemic blasts from the common form of childhood acute ‘lymphoblastic’leukaemia. (iv) Myeloid cells, including peripheral blood monocytes, and blast cells from acute myeloblastic and chronic granulocytic leukaemias showed an intense, diffuse reaction product (M‐like).

Blast crisis of chronic myeloid leukaemia (CML). II. Cell surface marker analysis of "lymphoid" and myeloid cases.

SUMMARY. Fourteen cases of Philadelphia chromosome (Ph1) positive chronic myeloid leukaemia in blast transformation have been investigated using cell surface markers. Morphologically eight cases were lymphoid and the remainder myeloid in appearance. All cases were negative with surface markers for thymocytes and T and B lymphocytes. Five of the lymphoid cases reacted with an antiserum specific for acute lymphoid leukaemia (ALL) of non‐T non‐B type and were also weakly reactive with a lymphocyte reactive antiserum. A sixth patient, whose blast cells were anti‐ALL negative (ALL‐) at presentation, subsequently developed central nervous system leukaemia with anti‐ALL positive (ALL+) blast cells in the CSF. In all cases the leukaemic blast cells showed greatly diminished expression of cholera toxin receptors when compared to granulocytic cells from the chronic phase of CML. This parallels weak or negligible expression of the cholera toxin receptor in ALL and AML.

Elicitation of Selective T and B Lymphocyte Responses by Cell Surface Binding Ligands

One of the motivating forces in lymphocyte biology is the belief that the behaviour of lymphocytes, and more particularly their response to antigen, provides a unique opportunity to analyse the molecular and cellular events involved in the induction and expression of differentiation. A major advance in the realisation of this potential was the finding (Nowell 1960) that quiescent non-dividing small lymphocytes could be triggered into a derepressed state of active growth and proliferation in vitro by phytohaemagglutinin (PHA). The response observed involves parameters common to many systems in which cell growth and proliferation are occurring, e.g. tissue regeneration and embryogenesis, and includes enhanced glycolysis, lysosomal enzyme activity, enhanced nuclear template activity, histone acetylation, DNA polymerase enzyme activity, etc. More specific changes indicative of differentiated activities of lymphocytes, e.g. immunoglobulin synthesis, may also occur, as will be discussed in this review. Although precise quantitation of the number of responding cells has yet to be reported it is clear that the number of cells reacting to PHA and similar stimulants Is considerably greater than one would expect to observe with a classical immunological response in which antigen recognition by relatively small numbers of cells occurs (i.e. cional selection). The response to PHA and other mitogens (see below) is therefore generally considered to be non-specific, i.e. it is a polyclonal lymphocyte response initiated by

TARGET CELL IN CHRONIC MYELOID LEUKÆMIA AND ITS RELATIONSHIP TO ACUTE LYMPHOID LEUKÆMIA

On the basis of membrane marker analysis with an antiserum made against acute lymphoblastic leukaemia and other immunological markers it is suggested that some chronic myeloid leukaemias (C.M.L.) and some acute lymphoblastic leukaemias (A.L.L.) originate in a common target cell or precursor. This is possibly a pluripotential stem cell or a closely related derivative. These leukaemic cells retain their undifferentiated membrane characteristics C.M.L. patients in blast crisis who are A.L.L.-antigen-positive and have terminal transferase enzyme activity might benefit from therapy usually given in typical Philadelphia-chromosome-negative A.L.L.

Blast Crisis of Chronic Myeloid Leukaemia (CML): I. PRESENTATION SIMULATING ACUTE LYMPHOID LEUKAEMIA (ALL)

SUMMARY. Seven patients presenting as an acute leukaemia caused difficulty in diagnosis. The lymphoid appearance of the blast cells either initially or during treatment suggested acute lymphoid leukaemia (ALL). In each case the Philadelphia chromosome was shown to be present thus suggesting that these cases were examples of chronic myeloid leukaemia (CML) presenting in blast crisis without a detectable chronic phase.

Lineage relationship of chronic lymphocytic leukemia and hairy cell leukemia: Studies with TPA

The tumor promoting agent TPA (phorbol ester; 1.6 X 10(-8)M) was used to induce the differentiation in vitro of B-chronic lymphocytic leukemia (B-CLL) cells from 14 untreated patients. The uninduced phenotype was SIg+, Mrbc+, RFT-1+, RFA-4-, FMC7-. After 72 h incubation with TPA, B-CLL cells became RFA-4+, FMC7+ and lost the capability of Mrbc rosetting. Large proportions of the induced cells also showed morphological and ultrastructural changes, such as undulating membranes and bleblike protusions and became strongly positive for tartrate resistant acid phosphatase (TRAP+) and also contained cytoplasmic immunoglobulins. These features are very similar to the features of hairy cell leukemia (HCL). These observations confirm previous clinical findings that B-CLL and HCL are related disorders of the B lineage. The development of hairy features in induced B-CLL and in HCL seems to be a malignancy-associated feature because the Mrbc+ normal B cells (B-CLL-equivalent cells) isolated from tonsil also develop TRAP positivity but no membrane aberrations.

Affordable CD4 T-cell enumeration for resource- limited regions: a status report for 2008.

The global struggle with human immunodeficiency virus (HIV) and the battle to develop affordable CD4 T‐cell counting technology are both unfulfilled goals in 2008. The need for such instrumentation is more critical now as implementation of antiretroviral therapy (ART) is in progress in many resource limited regions. Major scaling‐up efforts in rural situations are difficult to implement without laboratory infrastructure. CD4 T‐cell counting is especially critical when trying to reach individuals with HIV to have them enrolled in ART as soon as they qualify for treatment based on CD4 count.

Simplified cytometry for routine monitoring of infectious diseases

The interacting epidemics of HIV/AIDS, tuberculosis (TB) and malaria in resource‐poor areas of the world have created a critical need for rapid, simple, affordable apparatus and tests that will permit patients with these diseases to be promptly diagnosed and properly managed.

Recombinant interleukin 2 and anti-Tac influence the growth of enriched multipotent hemopoietic progenitors: proposed hypotheses for different responses in early and late progenitors.

Experiments were designed to evaluate the effect of recombinant IL-2 on growth of hemopoietic precursors from different sources (normal cord blood and bone marrow, and PB from CGL patients). For this purpose, combined cell sorting techniques and multipotent colony forming cell assays were used. A monoclonal antibody BI-3C5, which recognizes an antigen present on early lympho-myeloid cells as well as on all colony forming cells (CFU-GEMM assay), was used to enrich the studied populations. Double colour immunofluorescence techniques were performed to analyse the expression of Tac antigen on early progenitors. The results showed that rIL-2 had a stimulatory effect on growth of enriched progenitors from the three sources and surprisingly that addition of anti-Tac did not abolish this effect. On the contrary, anti-Tac enhanced even more growth of these sorted BI-3C5 precursors, suggesting a ligand action of the antibody. More interestingly, a low percentage of cord cells (1 in 1000) expressed both BI-3C5 and Tac antigens. The vast majority of cells did not concomitantly express both markers. The double labelled cells had a lymphoid-like morphology, high nucleus/cytoplasmic ratio and 2-3 nucleoli. The results will be discussed focusing on early and late stem cell growth.

POLYCLONAL MITOGENS AND THE NATURE OF B LYMPHOCYTE ACTIVATION MECHANISMS

ABSTRACT Three current competitive models of B lymphocyte activation involving either single or double signals are discussed. Experiments with polyclonal, mouse B cell mitogens have been designed to further investigate the validity of these hypotheses. Evidence is presented to suggest that direct activation of B lymphocytes via either surface immunoglobulins (using insolubilized haptens) or non-specific sites (lipopolysaccharide and pokeweed mitogeny) can occur. The mitogenicity of thymus–independent antigens was confirmed but found to be quantitatively unimpressive; its biological relevance is therefore questioned. No evidence could be obtained to support the view that activated complement or cyclic GMP are necessarily involved with the ‘2nd’ signal level. Evidence for B lymphocyte heterogeneity is presented in terms of proliferative responsiveness of spleen versus lymph node B cells. It is suggested that although some (principally IgM programmed) B cells can be directly activated with minimal second signal involvement, other (particularly IgG programmed) B lymphocytes have additional requirements which either operate during the early induction phase or post-inductively as potentiation mechanisms.