Importance of an 85 kDa membrane glycoprotein for a variety of cell-cell interactions

Expression of LFA-1 identifies different prognostic subgroups in patients with advanced follicle center lymphoma (FCL)

In a retrospective immunohistochemical study based on 27 patients with stage IV follicle center lymphoma (FCL) the expression of CD44standard (CD44s), LFA-1 (CD11a, CD18), VLA-4 (CD49d, CD29) and ICAM-1 (CD54) was analysed on lymphoma cells in bone marrow infiltrates. The results were correlated to clinical data and overall survival. Our data demonstrate that the expression of LFA-1 on lymphoma cells is predictive for the prognosis of patients with advanced FCL. In detail, patients exhibiting weak to moderate expression (+/++) of CD11 and CD18 showed a significantly shorter median survival (51 months and 33 months, respectively) than did those presenting with strong expression ( ) of the LFA-1 adhesion molecule (P = 0.04 and P = 0.0051, respectively). Furthermore, multivariate analysis identified CD18 as a new independent prognostic factor in patients with advanced FCL. Our findings emphasize the relevance of adhesion molecules for the pathology of FCL and give further support for their impact on clinical course and overall survival.

Effect of storage and ultraviolet B irradiation on CD14-bearing antigen-presenting cells (monocytes) in platelet concentrates

BACKGROUND

Ultraviolet B (UVB) irradiation of platelet concentrate (PCs) reduces platelet alloimmunization, but the mechanism of the effect is unclear. Evidence suggests that UVB may downregulate the expression of surface adhesion molecules on passenger antigen-presenting cells in PCs.

STUDY DESIGN AND METHODS

The effect of blood bank storage, platelet preparation from whole blood, and UVB irradiation on the quantitative expression of intercellular adhesion molecule-1 (ICAM-1, or CD54), HLA-DR, CD45, and CD11c on CD14-positive antigen-presenting cells (monocytes) was studied by using two-color flow cytometry.

RESULTS

Blood bank storage for 4 days resulted in upregulation of ICAM-1 and HLA-DR and downregulation of CD14 but left the expression of CD11c and CD45 unchanged. Preparation of PCs from fresh whole blood was associated with a rapid increase in CD11c without upregulation of ICAM-1 and HLA-DR. UVB irradiation before storage inhibited the upregulation of ICAM-1 and HLA-DR, resulted in accelerated downregulation of CD14, and was associated with increased loss of monocytes. Agitation of the PC bag during irradiation was of critical importance, since omission of agitation resulted in largely uninhibited upregulation of ICAM-1 but was still associated with significantly higher cell loss than that seen in unirradiated controls.

CONCLUSION

UVB exposure nonspecifically affects monocytes in PCs, resulting in downregulation of surface molecules that are important for antigen presentation, as well as in significant cell loss.

The importance of cellular adhesion for mesangial cell proliferation in serum sickness nephritis of the rat: a co-culture study of glomerular macrophages and mesangial cells

The role of cell-cell contact on activating mesangial cell proliferation by nephritic macrophage was investigated. Nephritic glomerular macrophages were obtained from serum sickness nephritis (SSN) rat kidneys at 14 days after the cessation of sensitization, when proliferating cells were most increased in the glomeruli in the course of the SSN. The effect of the nephritic macrophages on mesangial cell proliferation was greater than that of control by co-culture allowing cellular contact. However, nephritic macrophages did not enhance mesangial cell proliferation by co-culture without direct contact even though the nephritic macrophages were activated with lipopolysaccharides. Conditioned medium from co-culture of the nephritic macrophages and mesangial cells did not enhance mesangial cell proliferation. Anti-intercellular adhesion molecules (ICAM)-1 antibody inhibited mesangial cell proliferation by direct co-culture dose-dependently. From these results, cellular contact was important for stimulation of mesangial cell proliferation by macrophages and ICAM-1 participated in these interactions.

Involvement of adhesion molecules LFA-1 and ICAM-1 in osteoclast development

We report here that leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) are involved in osteoclast development. Osteoclast development was observed on co-culture of mouse spleen cells and mouse bone marrow derived clonal stromal cells, TMS-14, in the presence of 1 alpha, 25-dihydroxyvitamin D-3 (1 alpha, 25-(OH)2D3) for 8 days, and quantified with respect to tartrate-resistant acid phosphatase (TRACP) activity. When either one of the monoclonal antibodies (MAbs) to mouse LFA-1 and mouse ICAM-1 was added to the co-culture system, the TRACP activity was significantly inhibited. The experiment in which one-day treatment with each of these MAbs was performed during the 8 days of cultivation showed that the inhibitory effects of both MAbs on the TRACP activity at 8 days were observed from an early stage of the culture, but were more notable at a later stage (days 4-6). As the expression of ICAM-1 was observed on both spleen cells and TMS-14, we next examined whether the interaction between stromal cells and osteoclast progenitors or among osteoclast progenitors was more important for osteoclast development. To determine this, rat spleen cells and a MAb to rat ICAM-1 were used instead of those of mouse. When MAb to rat ICAM-1 or mouse ICAM-1 was added to the co-culture system of rat spleen cells and TMS-14, the inhibitory effect of the MAb to rat ICAM-1 was mainly observed at a later stage of the culture period and that of anti-mouse ICAM-1 antibody was only observed at an earlier stage. These results indicate that adhesion molecules LFA-1 and ICAM-1 may play a role in osteoclast development via interaction between stromal cells and osteoclast progenitors as well as among osteoclast progenitors.

Generation of recombinant, carbohydrate-free intercellular adhesion molecule-1 (ICAM-1) and ICAM-1 fragments in Escherichia coli and mapping of epitopes recognized by anti-ICAM-1 monoclonal antibodies

Intercellular adhesion molecule-1 (ICAM-1) has been shown to interact with the integrin leukocyte function associated antigen-1 (LFA-1) in a variety of cell-cell adhesion phenomena. Furthermore, it serves as a receptor for the majority of the Rhinoviruses and for Plasmodium falciparum-infected human erythrocytes. We generated recombinant, carbohydrate-free ICAM-1 and several ICAM-1 fragments by expression in Escherichia coli using the fusion protein expression system pUEX1-3. In Western blot and dot blot analyses we tested mAbs (7F7, 8B9, P3.58-BA3, -BA11, -BA14, -BA19, -BA21, -BA23, -BA24, -BA26, CL203.4 and 84H10) and a polyclonal antiserum directed against native ICAM-1 for their reactivity with these constructs. We were able to localize the binding site for the mAbs P3.58-BA3, -BA11, -BA14, -BA19, -BA21, -BA23, -BA24 and -BA26 at domain 5, whereas the mAbs 7F7, 8B9, CL203.4 and 84H10 did not recognize the recombinant, carbohydrate-free ICAM-1. Our findings suggest the presence of an immunodominant epitope on domain 5 of ICAM-1.

A monoclonal antibody directed against the human intercellular adhesion molecule (ICAM-1) modulates the release of tumor necrosis factor-alpha, interferon-gamma and interleukin 1

ICAM-1 is a cell surface glycoprotein which is one of the ligands for the leukocyte function-associated antigen (LFA-1). It is involved in leukocyte adhesion to endothelial cells as well as in immune functions requiring cell-cell contact. The quantitative expression of ICAM-1 in various cell types can be either induced or enhanced by treatment with cytokines, such as interferon-gamma (IFN-gamma), tumor necrosis factor (TNF)-alpha or interleukin 1 (IL 1), a phenomenon which results in the augmentation of binding to LFA-1-positive cells. In contrast, treatment with anti-ICAM-1 antibodies blocks this binding. A monoclonal antibody (mAb), termed 7F7, which recognizes an epitope on ICAM-1, was used to investigate the role of ICAM-1 in cytokine production by T lymphocytes and monocytes. Production of TNF-alpha. IFN-gamma and IL1 was significantly inhibited (p less than 0.01) by the incubation of mAb 7F7 with phytohemagglutinin-activated blood mononuclear cells (MNC) or isolated E rosette-positive T lymphocytes. The maximal level of inhibition was reached with 1 microgram/ml of purified antibody. A similar inhibition was obtained using saturating concentrations of 400 microliters/ml of mAb 7F7 hybridoma supernatant corresponding to an inhibitory activity of 1 microgram of purified mAb. In contrast, granulocyte/macrophage-colony-stimulating factor release showed a heterogeneous response over five experiments with an increase found in three experiments and a decrease in two experiments. Addition of increasing concentrations of supernatant or purified mAb to unstimulated MNC or T lymphocyte cultures had no effect on cytokine release. The observed inhibition of the production of TNF-alpha. IFN-gamma and IL 1 by antibody-mediated blockade of the ICAM-1 structure probably represents a negative circuit that serves to tune the activation of leukocytes and to avoid an overproduction of cytokines.

Cytokine-induced generation of multinucleated giant cells in vitro requires interferon-gamma and expression of LFA-1

Multinucleated giant cells (MGC), which are a common feature of various pathologic states, were generated in vitro by cytokine-stimulation of human peripheral blood monocytes. As expected, conditioned medium, i.e. the supernatant of concanavalin A-stimulated peripheral blood mononuclear cells, readily caused generation of MGC. Addition of a monoclonal antibody (mAb) against interferon-gamma (IFN-gamma) completely abrogated this effect. IFN-gamma alone, however, had a much smaller effect than the conditioned medium. All other cytokines tested [including interleukin (IL)2, IL4 and tumor necrosis factor-alpha, which are known to activate monocytes] did not induce MGC nor did they enhance the effect of IFN-gamma. Formation of MGC could almost entirely be inhibited by mAb to the alpha or beta chain of LFA-1 and to a lesser extent by relatively high concentrations of a mAb against ICAM-1, one of the ligands of LFA-1. In contrast to the anti-IFN-gamma mAb that had no significant effect on the formation of monocyte clusters, mAb against LFA-1 inhibited clustering very efficiently. Antibodies directed to a number of different antigens present on the surface of monocytes (alpha chains of CR3 and CR4, HLA class I and II molecules, CD14 and CD16 antigens) had little or no effect on the generation of MGC. IFN-gamma, but not the concanavalin A-induced supernatant clearly enhanced expression of LFA-1 and ICAM-1 on monocytes. The results indicate that cytokine-induced generation of MGC is not possible without IFN-gamma, but most probably additional factor(s) enhance this effect. The mechanism(s) by which IFN-gamma promotes monocyte fusion apparently includes, among others, up-regulation of LFA-1 whose expression seems to be necessary but not sufficient for fusion.

Importance of ICAM-1 for accessory cell function of monocytic cells

We investigated to what extent the adherence molecule ICAM-1 is important for the accessory cell function of cells of the monocyte lineage. A monoclonal antibody to ICAM-1, 7F7, inhibited the accessory cell function of human peripheral blood monocytes cultured in the presence of serum for 1-3 days. Monocyte, cultured for 4-7 days still expressed ICAM-1 but their accessory cell function was no longer inhibited by the antibody 7F7. Dendritiform accessory cells, obtained by culture of peripheral blood monocytes in serum free medium for 1-2 days also expressed ICAM-1 and their capacity to stimulate T-cells was also abrogated by antibody 7F7. These findings suggest that ICAM-1 on the surface of accessory cells of a certain differentiation stage seems to contribute to the capacity of these cells to stimulate T-cells but, that in some situations accessory cell function can occur normally without requiring ICAM-1 dependent cell to cell interactions.

Hyporesponsiveness of "naive" (CD45RA+) human T cells to multiple receptor-mediated stimuli but augmentation of responses by co-stimuli

Much remains to be clarified the functional capacities of the two major reciprocal subsets of human CD4+ cells which we interpret to be naive and memory cells. CD4+ naive (CD45RA+, LFA-3-) and memory (CD45R0+, LFA-3+) cells were rigorously purified by immunomagnetic negative selection. Their proliferation was measured in response to four protocols of receptor-mediated activation: soluble anti-CD3 mAb, plastic-immobilized anti-CD3 mAb, activating pairs of anti-CD2 mAb, and "superantigens" staphyloccocal enterotoxins A and B (SEA and SEB). Naive cells proliferated much less than memory cells to each of these four regimens although their capacity to respond was demonstrated by strong PHA-induced proliferation. Although three of the regimens depend on autologous monocytes, poorer naive cell responses are also observed to anti-CD3 mAb immobilized on plastic in the absence of monocytes; this implies an intrinsic hyporesponsiveness of naive cells, independent of their potentially weaker interaction with monocytes. Naive cells proliferated less than memory cells to superantigens SEA and SEB over a wide dose range; this assumes particular importance because such superantigens are believed to more closely mimic antigen-specific stimulation than anti-CD3 mAb. The possibility was explored that hyporesponsiveness of naive cells reflects the fact that naive cells require additional co-stimuli to facilitate their activation. In support of this concept, we observed that proliferation of naive cells to anti-CD3 mAb and SEA or SEB (but not to anti-CD2 mAb pairs) was consistently enhanced by pre-activation of monocytes present in the culture. Naive cell proliferative responses were augmented further in cultures supplemented with interleukin (IL) 1 beta and IL 6 or exposed to the co-stimulating mAb anti-CD28 and anti-CD44. The pattern of augmentation was dependent on the specific triggering regimen: anti-CD44 mAb was particularly effective in augmenting the response to superantigens, anti-CD28 mAb for the anti-CD3 response and IL 1 beta/IL 6 for that induced by anti-CD2 mAb pairs. With particular combinations of stimulus/co-stimuli naive cell proliferation was as strong as that of memory cells. We interpret these findings to indicate that naive cells are capable of responding to antigen, but that such responses are critically dependent on the available co-stimuli in vivo.

Roles of adhesion molecules in T-cell recognition: fundamental similarities between four integrins on resting human T cells (LFA-1, VLA-4, VLA-5, VLA-6) in expression, binding, and costimulation

This review summarizes our recent work on expression and function of 4 integrins on resting human CD4+ T cells. Three themes are highlighted: multiplicity of molecular pathways of adhesion, regulation of adhesion, and costimulation by adhesion molecules. Four distinct receptor/ligand interactions have been elucidated: LFA-1/ICAM-1, VLA-5/fibronection, VLA-4/fibronectin, and VLA-6/laminin. Our studies indicate fundamental similarities in function and regulation of these four receptor/ligand interactions: 1) acute activation of the T cell (by CD3/TCR crosslinking or by PMA) induces rapid but transient integrin binding function; and 2) higher expression of each integrin on memory T cells compared to naive T cells results in greater binding of memory cells to each ligand. The identification of T-cell integrins (VLA-4, VLA-5, VLA-6) which interact with ECM components directs attention to the potential importance of T-cell interactions with ECM components which either may be immobilized in ECM or which may act as molecular bridges between cells. The existence of multiple adhesion pathways, of multiple ligands for a single receptor (such as LFA-1/ICAM-1 and LFA-1/ICAM-2), multiple receptors for a single ligand (such as VLA-4/FN and VLA-5/FN), and regulation of ligand expression (ICAM-1) provides opportunities for co-operativity, rebundancy and diversity which the T cell utilizes to exquisitely regulate its adhesive interactions. The thesis that adhesion molecules can be multifunctional receptors that also influence signalling is demonstrated by our findings that each of these integrin receptor/ligand interactions is capable of providing a potent costimulatory signal to CD3-mediated T-cell activation. The importance of interactions of T-cell integrins with their cell surface and ECM ligands is discussed with respect to T-cell migration, differentiation and recognition. Analysis of the precise mechanisms by which T cells regulate and exploit these multiple receptor/ligand interactions and the resulting functional consequences of those interactions will be exciting areas of future research.

Expression of 7F7-antigen, a human adhesion molecule identical to intercellular adhesion molecule-1 (ICAM-1) in human carcinomas and their stromal fibroblasts

The 7F7-antigen is a widespread 85-kDa membrane adherence molecule involved in heterotypic adhesion between PHA-blasts and fibroblasts. Immunofluorescence analysis of COS cells transfected with clone pICAM-I indicated that 7F7-antigen is identical with ICAM-I, the ligand for the contact molecule LFA-I. We have investigated the expression of ICAM-I on several human carcinomas. Tumor cells in most carcinomas, with the exception of squamous-cell carcinomas, expressed very little ICAM-I or none at all. In contrast, marked expression of this molecule was observed on fibrous tissue in the vicinity of carcinoma cells, its intensity correlating with lymphatic infiltration in these tumors. We also examined the expression of ICAM-I on carcinoma cell lines and its induction by treatment with interferon-gamma (IFN-gamma). The inducibility of ICAM-I expression on cultured fibroblasts by several lymphokines suggests that the expression of ICAM-I in the vicinity of carcinoma cells is effected by lymphokines produced by activated lymphocytes/macrophages within the tumor.