Martin Hadam

Reference: CD Antigens 2002.

The Proceedings of the 7th Human Leukocyte Differentiation Antigen (HLDA) Workshop are about to be published, detailing more than 80 new CD specificities. The next Workshop, planned for 2004, will continue this process, and a number of candidate CD molecules in the literature, identified by antibody

Analysis of mast cells in rheumatoid arthritis and osteoarthritis by an avidin-peroxidase staining

SummaryAs demonstrated by labeling with peroxidase, avidin was found to bind selectively and distinctly to mast cell granules. Inhibition studies suggested that avidin is bound by heparin. Based on this new mast cell staining procedure, mast cell distribution in the inflamed synovium of rheumatoid arthritis (RA) and osteoarthritis (OA) has been investigated. In the subsynovial layer, a significant decrease in mast cell numbers was observed in RA-synovium when compared with OA-synovium. This decrease correlated with the presence of lining cell ulcers and granulation tissue and can be interpreted as the result of mast cell degranuation induced by complement-mediated or immune complex-triggered mechanisms.

Predominant immunoglobulin gene rearrangements in two patients with immunodeficiency: restricted use of V gene segments and DNA hypermethylation.

The majority of common variable immunodeficiencies (CVID) is caused by intrinsic B cell defects which impede distinct stages of B cell differentiation. B cell differentiation is accompanied by the rearrangement of immunoglobulin (Ig) genes. The first step in the rearrangement process is the assembly of IgH genes, and subsequently, IgL genes are rearranged. During B cell maturation, Ig genes are demethylated in a stepwise, locus-specific manner. Here, we examined the Ig gene rearrangements of four patients with classical CVID and of one child suffering from an unusual immunodeficiency associated with CD5+ B cell lymphocytosis. In one of the four adult patients with CVID, we observed a predominant type of VHDJH-gene rearrangement. In the child, different polyclonal VHDJH-gene rearrangements were found together with a predominant type of kappa light chain gene rearrangement. The rearranged kappa chain genes were methylated (as in the pre-B cell stage). These findings together with the cell phenotype analysis and the clinical course of the disease in the child suggests that in some patients with primary immunodeficiency a maturation arrest may occur in B cells leading to a predominant Ig V gene rearrangement.

T-cell prolymphocytic leukemia (T-PLL) with unique surface phenotype

SummaryLeukemic cells of a 19 year old patient with prolymphocytic leukemia of T-cell type (T-PLL) were characterized by surface markers and immunologic functions. Phenotypic analysis using a large panel of monoclonal antibodies corresponding to the clusters (CD) of differentiation antigens established on the leukocyte Typing Workshops I and II [1, 16] revealed a unique T-cell phenotype not yet reported in the literature: CD 1 (T 6)−, CD 2 (T 11)+, CD 3 (T 3)+, CD 4 (T 4)−, CD 5 (T 1)−, CD 6 (T 411)+, CD 7 (Leu 9)+, CD 8 (T 811)−, CD 10 (J 5)−, CD 11 (M 522)+, CD 12 (M 67)−, CD 13 (My 7)−, CD 14 (Mo 2)−, CD 16 (Vep 13, 3 G 8, Leu 11)+, CD 18 (MHM 23)+, CD 19 (B 4)−, CD 20 (B 1)−, CD 25 (TAC)−, MHC-class II (HLA-DR, HLA-DQ)−, NKH 1 A+, Leu 7−. Despite the expression of surface structures associated with natural killer (NK) function (CD 16, CD 18, NKH 1 A) the T-PLL cells were inactive in NK assays in vitro. Low in vitro ADCC activity was detectable. This unusual T-PLL phenotype might help to identify a new distinct T-cell differentiation stage.

MANIPULATIONS OF NATURAL CYTOTOXICITY IN TUMOR PATIENTS VIA BCG

Publisher Summary This chapter highlights the manipulations of natural cytotoxicity in tumor patients via bacillus calmette-guerin (BCG). Local BCG stimulation induces a systemic short-lasting cytotoxicity response that can be easily monitored in the peripheral blood by use of the 3H-proline release test. This reaction seems to depend on the number of BCG organisms applied. Whether this tumor-directed response measured in vitro has a clinical significance is not yet established, although a correlation between the development of cytotoxicity and progression of the tumor disease was recently reported. It is also unclear whether potentiation of cytotoxicity induced by lower BCG doses parallels an increase in cellular tumoricidal activity in vivo. The actual BCG dose leading to such an augmentation of cytotoxicity seems to have a distinct optimum that varies considerably with the individual patient. It has been reported that BCG can render lymphocytes from healthy donors cytotoxic rather selectively for melanoma cells by mere incubation with the vaccine in vitro.

Human E-rosette forming lymphocytes exhibiting antibody-dependent cytotoxic activity

Antibody-dependent cell-mediated cytoxicity (ADCC) is a very efficient in vitro cytocidal reaction in which effector cells bind to, and kill target cells that are coated with antibodies. Both in animals and in man, different types of effector ceils have been identified depending on the ADCC-system used [10]. The cytolytic activity of these cells, operationally defined as K-cells, is linked to the presence of membrane receptors (FcRs) exhibiting a strong binding activity for the Fc-portion of immunoglobulins [7]. In most systems, K-ceils were found to be mononuclear cells expressing FcRs [8] as well as complement receptors [ 16], but lacking the typical surface markers for T-and B-lymphocytes, i.e. surface immunoglobulin (SIg) or receptors for sheep erythrocytes (SRBC) [7, 8]. Thus, the precise nature and origin of the K-cells remain uncertain. Antibodies inducing K-cell killing belong mainly to the IgG-class [7] and are also called lymphocyte-dependent antibodies (LDA). Since ADCC is a highly sensitive system in which target ceils are killed by minute amounts of LDA and since tumor directed LDAs have been found in tumor patients [5], this type of cytocidal mechanism is supposed to be of considerable importance for the in vivo immune response to tumors. It was therefore of interest to study the ADCC against tumor cells in tumor patients, in order to classify the antibodies involved and to isolate and characterize the effector cells in this system. The experiments reported here were performed with effector cells and sera obtained from patients with malignant melanoma. The cytolytic reactions were measured in an isotope release test {13] using aH-proline labeled cultured melanoma ceils as target cells. In this report, evidence is presented that human T-lymphocytes can cooperate with IgG-antibodies from melanoma patients in the lysis of melanoma cells in vitro. In addition, it is shown, that, by cocultivation with allogeneic tumor cells, K-cell-activity can be generated in a population of almost pure human T-marker bearing cells and that synchronously with the generation of K-cell activity, increase of FcR-bearing cells is found.