Modulation of interferon-gamma-induced major histocompatibility (MHC) and CD14 antigen changes by lipophilic muramyltripeptide MTP-PE in human monocytes

Modulating LPS signal transduction at the LPS receptor complex with synthetic Lipid A analogues

Sepsis, defined as a clinical syndrome brought about by an amplified and dysregulated inflammatory response to infections, is one of the leading causes of death worldwide. Despite persistent attempts to develop treatment strategies to manage sepsis in the clinical setting, the basic elements of treatment have not changed since the 1960s. As such, the development of effective therapies for reducing inflammatory reactions and end-organ dysfunction in critically ill patients with sepsis remains a global priority. Advances in understanding of the immune response to sepsis provide the opportunity to develop more effective pharmaceuticals. This article details current information on the modulation of the lipopolysaccharide (LPS) receptor complex with synthetic Lipid A mimetics. As the initial and most critical event in sepsis pathophysiology, the LPS receptor provides an attractive target for antisepsis agents. One of the well-studied approaches to sepsis therapy involves the use of derivatives of Lipid A, the membrane-anchor portion of an LPS, which is largely responsible for its endotoxic activity. This article describes the structural and conformational requirements influencing the ability of Lipid A analogues to compete with LPS for binding to the LPS receptor complex and to inhibit the induction of the signal transduction pathway by impairing LPS-initiated receptor dimerization.

Th1/Th2 balance in preeclampsia

The syndrome of preeclampsia has previously been ascribed to generalized maternal endothelial dysfunction, poor placentation and excessive maternal inflammatory response. Recent reports suggest that preeclampsia is associated with a Th1 predominant profile and may be considered as a failure of the tolerance system allowing the second physiological trophoblastic invasion. In this review, we discuss that Th1 predominant immunity is closely related to inflammation, endothelial dysfunction and poor placentation.

Interleukin-12 secretion by peripheral blood mononuclear cells is decreased in normal pregnant subjects and increased in preeclamptic patients

PROBLEM

It has been reported that T-helper (Th) 2 dominance in normal pregnancy shifts to Th1 dominance in preeclampsia. Peripheral blood mononuclear cell (PBMC) production of interleukin (IL)-12, which induce Th1 responses, has not been compared between these clinical states.

METHOD OF STUDY

Peripheral blood mononuclear cell from 35 non-pregnant women, 35 healthy pregnant women, 12 mildly preeclamptic patients, and 15 severely preeclamptic patients were cultured for 24 hr. IL-12 secretion was determined by enzyme-linked immunosorbent assay (ELISA). Th1/Th2 ratios in PBMC were determined flow-cytometrically, and the amounts of HLA-DR and CD14 expression on the monocytes were obtained by flow cytometry.

RESULTS

Peripheral blood mononuclear cell from healthy pregnant subjects secreted less IL-12 than non-pregnant women. PBMC from severely preeclamptic patients secreted more IL-12 than those from healthy pregnant subjects, while IL-12 secretion in mild preeclampsia resembled secretion in normal pregnancy. Th1/Th2 ratios correlated were positively with IL-12. Increased HLA-DR antigens and reduced CD14 expression, suggesting monocyte activation, were observed in preeclamptic patients, although monocyte counts were unchanged.

CONCLUSION

Decreased IL-12 secretion by PBMC may cause Th2 dominance in normal pregnancy, while increased IL-12 secretion by activated monocytes may cause Th1 dominance in preeclampsia.

A comparative analysis of cytokine production and tolerance induction by bacterial lipopeptides, lipopolysaccharides and Staphyloccous aureus in human monocytes

Monocytes (MO) and macrophages (MAC) are important producers of cytokines involved in the pathophysiology of bacterial sepsis. Most studies concentrate on the effects of bacterial lipopolysaccharides (LPS) regarding the induction of cytokine gene expression and secretion in MO/MAC. Here we report that besides LPS, the synthetic lipoprotein analogue lipopeptide N-palmitoyl-S-(2,3-bis(palmitoyl)-(2RS)-propyl)-(R)-cysteinyl-alanyl- glycine (Pam3-Cys-Ala-Gly), another component of the outer membrane of Gram-negative bacteria, as well as heat-killed Staphyloccocus aureus (S. aureus/SAC) are potent stimuli for cytokines in human MO. For all three investigated stimuli we found an individual pattern of cytokine induction: LPS was most potent in inducing interleukin-6 (IL-6) synthesis, whereas for tumour necrosis factor-alpha (TNF-alpha) secretion SAC was the best stimulus. Comparable amounts of IL-8 were induced by either LPS or Pam3-Cys-Ala-Gly, with SAC being less effective even at higher concentrations. The addition of serum led to an increase in LPS-, SAC- and Pam3-Cys-Ala-Gly-stimulated TNF-alpha secretion, indicating that the presence of serum is critical not just for LPS stimulation. Furthermore, as is known for LPS, Pam3-Cys-Ala-Gly and SAC rendered MO refractory to a second bacterial stimulus. Pam3-Cys-Ala-Gly and SAC induced tolerance for itself, but LPS could partially overcome this effect. As the CD14 molecule is discussed as a common receptor for different bacterial components, we investigated whether the TNF-alpha response of MO could be blocked by anti-CD14 antibodies. MY4, a CD14 antibody, selectively blocked the TNF-alpha secretion induced by LPS but not by Pam3-Cys-Ala-Gly or SAC. In summary, we conclude that besides LPS, lipopeptide Pam3-Cys-Ala-Gly and SAC are potent stimuli for human MO, while the mechanisms of activation seem to be partially different from LPS.

Immunodepressive effects of LPS on monocyte CD14 in vivo

Having previously reported that septic patients displayed lower levels of monocyte CD14 (endotoxin receptor) as compared to normal individuals, we were interested in the hypothesis that lipopolysaccharide (LPS) modulates levels of monocyte CD14 in vivo. We examined CD14 expression in 13 human volunteers who were given a non-lethal injection of Escherichia coli LPS (4.0 ng/kg). Monocyte CD14 was assayed by direct immunofluorescent determination with appropriate anti-CD14 monoclonal antibodies using flow cytometry. To test for cell responsiveness, monocytes were additionally examined following in vitro stimulation by phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (FMLP). Following LPS infusion, all patients displayed significant monocytopenia and responded with fever and tachycardia. Plasma samples demonstrated elevated levels of TNF alpha. CD14 expression was down-regulated by 52% on monocytes obtained 3 hr following LPS infusion (P < 0.05, vs. pre-LPS levels). Monocytes obtained pre-LPS infusion were down-regulated following in vitro stimulation by PMA to levels 72 +/- 8% and by FMLP to levels 75 +/- 5% of unstimulated control cells. In contrast, monocytes obtained 3 hr post-LPS infusion failed to respond to PMA or FMLP with significant down-regulation. LPS down-regulated CD14 expression on monocytes in vivo and LPS also blunted the ability of monocytes to respond to other stimuli. We conclude that LPS desensitizes monocytes to itself and thereby renders an immunodepressive effect on these cells.

Unaltered monocyte function in patients with major depression before and after three months of antidepressive therapy

Monocyte phenotypes and functions were studied in 22 patients with major depression, and compared with those of 22 matched healthy controls. Immune measures were performed before and after dexamethasone suppression, and after 4 and 12 weeks of moclobemide therapy in patients. Seven patients terminated after 4 weeks because of treatment failure; 11 out of 15 patients responded to therapy after 12 weeks. Monocyte human leukocyte antigen class II and CD14 antigen expression, tumor necrosis factor production, and plasma interferon-gamma and neopterin did not differ in patients before treatment and controls. The reaction to dexamethasone was also similar in patients and controls. Neither antidepressive treatment per se nor the clinical response to it affected any immunological parameter. In conclusion, corticosteroid-controlled monocyte functions were similar in untreated and treated depressed patients and in controls, and unrelated to the clinical course of the disease.

Bacterial cell wall products increase monocyte HLA-DR and ICAM-1 without affecting lymphocyte CD18 expression

Bacterial cell wall products such as lipopolysaccharide (LPS) and muramyl dipeptide (MDP) have the capacity to enhance immune responses to antigens. The expression of surface class II major histocompatibility antigens and the costimulatory receptors CD18 and CD54/ICAM-1 (intercellular adhesion molecule) was used to evaluate the comparative influence of these immunostimulators. On monocytes, both LPS and MDP increased the expression of human leukocyte antigen (HLA)-DR (maximal at 6 hr), CD18 (maximal at 1-3 hr), and ICAM-1 (maximal at 18-24 hr for LPS and 12 hr for MDP) without increasing the production of superoxide. MDP-induced ICAM-1 expression on monocytes returned to baseline values after 12 hr. On lymphocytes, only LPS increased ICAM-1 (after 18 hr) without affecting CD18, and a differential analysis demonstrated a generalized ICAM-1 upregulation in lymphocyte subsets after 18 hr: the most pronounced effect was measured in natural killer cells, followed by CD8(+) T cells, B cells, and CD4(+) T cells. MDP did not alter ICAM-1 or CD18 expression on lymphocytes. These similar but smaller effects of MDP may, in part, explain the lesser toxicity of MDP when compared to LPS.

CD14 expression in injured patients correlates with outcome

OBJECTIVE

The authors determined the correlation between monocyte CD14 expression and outcome in severely injured patients.

SUMMARY BACKGROUND DATA

Human leukocyte antigen-DR (HLA-DR) expression CD14 positive monocytes correlates with the development of major infection and subsequent death in severely injured patients. Recent studies show that CD14 is not only a marker for mature monocytes, but also is an important endotoxin/lipopolysaccharide receptor.

METHODS

Flow cytometry data obtained by dual staining techniques (CD14 and HLA-DR) of monocytes in 213 severely injured patients were analyzed over a 30-day period. Outcome criteria included survival and the development of both major and minor infections.

RESULTS

The percentage of cells expressing CD14 (%CD14) correlated with clinical outcome, reaching significance (p < 0.05) between noninfected survivors (n = 74) and nonsurvivors (n = 21) at days 3, 7, 11, 17, 24, and 30. At days 3, 7, and 17, the %CD14 also was different between noninfected and infected survivors. After 7 days, differences were only seen between survivors and nonsurvivors (p < 0.05). The mean fluorescence intensity (MC CD14) in monocytes of all patients was significantly reduced at day 3 compared with day 1 and remained low for 30 days (p < 0.05). The nonsurvivor group had consistently low MC CD14 values, which were significant at day 5 (p < 0.05).

CONCLUSIONS

In addition to HLA-DR expression, CD14 expression on monocytes is an indicator of clinical outcome after injury and could represent a more precise target for treatment.

Human monocyte CD14 is upregulated by lipopolysaccharide

Membrane CD14 is involved in lipopolysaccharide (LPS)-induced monocyte activation; it binds LPS, and antibodies against CD14 block the effects of low-dose LPS. It is unknown how LPS regulates its own receptor CD14 in vitro. Therefore, we investigated the effects of LPS on CD14 mRNA and membrane and soluble CD14 (mCD14 and sCD14, respectively) in human monocytes and macrophages. No changes were observed during the first 3 h of LPS stimulation. After 6 to 15 h, LPS weakly reduced CD14 mRNA and mCD14 and transiently enhanced sCD14 release. A 2-day incubation with LPS caused increases in the levels of CD14 mRNA (2-fold), mCD14 (2-fold), sCD14 (1.5-fold), and LPS-fluorescein isothiocyanate binding (1.5-fold); a 5-h incubation with LPS was sufficient to induce the late effects on mCD14 and sCD14. The maximal effect on mCD14 and sCD14 was reached with > or = 1 ng of LPS per ml; the proportional distribution of the two sCD14 isoforms was not modified by LPS. Besides rough and smooth LPS, lipid A, heat-killed Escherichia coli, lipoteichoic acid, and Staphylococcus aureus cell wall extract (10 micrograms/ml) caused similar increases of mCD14. The LPS effect was blocked by polymyxin B but not by anti-tumor necrosis factor alpha, anti-interleukin-6, anti-gamma interferon, and anti-LPS-binding protein. LPS-induced tumor necrosis factor alpha production was abolished after a second 4-h challenge. In contrast, the LPS-induced increases CD14 mRNA, mCD14, and sCD14 were stronger and appeared earlier after a second LPS challenge. In conclusion, CD14 is transcriptionally upregulated by LPS and other bacterial cell wall constituents.

Interleukin-4 inhibits lipopolysaccharide-induced expression of prostaglandin H synthase-2 in human alveolar macrophages

Several studies have shown that interleukin-4 (IL-4) down-regulates synthesis of prostaglandin E2 (PGE2). We evaluated the mechanisms for this suppression in human alveolar macrophages (HAMs). Normal HAMs were obtained from healthy nonsmoking volunteers. The cells either remained unstimulated, or were exposed to 10 micrograms/ml of lipopolysaccharide (LPS) and/or various amounts of IL-4. LPS alone induced the synthesis of large amounts of PGE2 and prostaglandin H synthase-2 (PGHS-2) protein. This effect of LPS was suppressed by increasing amounts of IL-4. Expression of LPS-induced PGHS-2 mRNA was also inhibited by IL-4. In addition, IL-4 inhibited expression of CD14, which is a receptor for LPS bound to the LPS-binding protein (LBP). We conclude that IL-4 down-regulates LPS-induced release of PGE2, by reducing expression of the enzyme, PGHS-2. One potential mechanism for this effect of IL-4 is a reduced expression of CD14, which is the LPS-LBP receptor.

Effects of anti-CD18 and LPS on CD14 expression on human monocytes

In this study we show that the cytokine stimulatory effect of LPS on human monocytes is enhanced by addition of monoclonal antibodies against CD18 (alpha CD18 MoAbs). Incubation of monocytes with alpha CD18 MoAbs overnight increased the CD14 expression as detected by Leu-M3, but not with My-4. These results indicate that CD18 participates in LPS-induced TNF-alpha production as well as in regulating CD14 expression on monocytes. Addition of LPS to monocytes resulted in a reduction in the CD14 expression after 1/2, 1, 2 and 4 h, but increased CD14 expression was seen after LPS stimulation overnight. By doing double labelling of the monocyte population for CD14 and CD16 it was found that the reduction in CD14 expression occurred in the CD14+/CD16+ sub-population, while the increase in CD14 expression was seen in both the CD14+/CD16- and the CD14+/CD16+ cells. alpha CD14 MoAbs that were able to inhibit LPS-induced cytokine production from monocytes (3C10 and My-4) were considerably less able to detect the increase in CD14 expression after LPS stimulation than alpha CD14 MoAbs that did not inhibit LPS-induced cytokine production (Leu-M3 and alpha CD14Serva). Our data indicate that My-4 and Leu-M3 define two populations of CD14+ cells on LPS stimulated human monocytes.

Selective modulation of lipopolysaccharide-induced death and cytokine production by various muramyl peptides

Pretreatment of animals with the adjuvant muramyl dipeptide enhances both the production of circulating tumor necrosis factor and the sensitivity to the lethal effect of a lipopolysaccharide (LPS) challenge. The present study examined the capacity of various adjuvant muramyl dipeptide derivatives to potentiate responsiveness to LPS administration. Cytokine levels in serum were determined at various time intervals after LPS administration by bioassays and immunoassays; the cytokines examined were tumor necrosis factor, interleukin-1, interleukin-6, and gamma interferon. The time course of cytokine response was not modified by the pretreatment, but most of the levels were strongly enhanced. However, of the four compounds which were found to be potent priming agents, only two caused an increased sensitivity to LPS lethality, showing that elevated titers of cytokines in serum were not correlated with host sensitization. Interestingly, previous studies have shown that these two compounds also display neurobiological properties, implying a possible role of the central nervous system in LPS lethality. However, two hydrophilic derivatives with low activity as priming agents were capable of decreasing the toxicity of LPS when given after the challenge in galactosamine-sensitized mice. These results illustrate the diversity of responses elicited by immunological priming. They raise unanswered questions on the importance of endogenous mediators in the pathophysiological alterations during toxic shock.

Adjuvants: current status, clinical perspectives and future prospects

Adjuvants represent a key issue for vaccines currently under development. Adjuvanticity is linked to the ability to stimulate the T-cell subsets that control the major features of specific immune responses: CD4+ TH1 and TH2 cells and CD8+ cells involved in cytotoxic T lymphocyte responses. Some well-defined immunomodulatory compounds can achieve this stimulation by inducing selective production of appropriate cytokines. Françoise Audibert and Luc Lise review the development of adjuvants and discuss how their combination with suitable vehicles should allow customization of adjuvant preparations capable of inducing protective immune responses better adapted to each type of pathogenicity.

Adjuvants: current status, clinical perspectives and future prospects

Adjuvants represent a key issue for vaccines currently under development. Adjuvanticity is linked to the ability to stimulate the T-cell subsets that control the major features of specific immune responses: CD4+ TH1 and TH2 cells and CD8+ cells involved in cytotoxic T-lymphocyte responses. Some well-defined immunomodulatory compounds can achieve this stimulation by inducing selective production of appropriate cytokines. Françoise Audibert and Luc Lise review the development of adjuvants and discuss how their combination with suitable vehicles should allow customization of adjuvant preparations capable of inducing protective immune responses better adapted to each type of pathogenicity.

The effects of interferon-gamma and bacterial lipopolysaccharide on CD14 expression in human monocytes

CD14 has been reported to be the lipopolysaccharide (LPS)-LPS binding protein receptor. The effects of interferon-gamma (IFN-gamma) on CD14 expression have not been clearly established. The purpose of this investigation was to examine the effects of IFN-gamma alone and IFN-gamma followed by bacterial LPS on CD14 expression. Human peripheral blood monocytes were isolated by counterflow centrifugal elutriation (CCE). Monocytes were cultured for 48 h with IFN-gamma alone or for 24 h with IFN-gamma followed by LPS for a second 24 h. IFN-gamma alone caused a down-regulation of CD14 expression, as assessed by flow cytometry, relative to CD14 expression in untreated monocytes. In addition, CD14 expression was even more significantly down-regulated after IFN-gamma pretreatment followed by either Prevotella intermedia or Salmonella typhimurium LPS. Likewise, the percentage of CD14+ monocytes decreased after IFN-gamma alone and even more dramatically after IFN-gamma treatment followed by either LPS. This study clearly demonstrated that IFN-gamma down-regulates CD14 expression and that LPS following IFN-gamma pretreatment potentiates this effect.

Prolonged interferon-gamma application by subcutaneous infusion in cancer patients: differential response of serum CD14, neopterin, and monocyte HLA class I and II antigens

This study reports on biological response modification induced by prolonged continuous subcutaneous (s.c.) infusion of recombinant interferon-gamma (rIFN-gamma) with particular attention to changes of soluble CD14. This glycoprotein with an unknown function is derived from myeloid cells carrying membrane CD14, which is the receptor for lipopolysaccharide (LPS)-LPS-binding protein (LBP) complexes. Fifteen metastatic cancer patients received weekly escalating doses of rIFN-gamma starting at either 50 or 100 micrograms/24 h and increasing up to 400 micrograms/24 h for a median duration of 6 weeks. The maximum tolerated dose was higher (200 micrograms/24 h) with the lower (50 micrograms/24 h) starting dose. Biological activity of rIFN-gamma was evaluated by weekly measurements of CD14, neopterin, and beta 2-microglobulin concentrations in serum as well as monocyte HLA class I and II antigen expression and tumor cytotoxicity. Serum IFN-gamma concentrations increased 20-fold within 4 weeks of therapy. The levels were correlated to the mean dose (r = 0.95, p less than 0.05). Among the biological markers, two patterns were observed. First, serum CD14 concentration and expression of monocyte HLA class II antigens increased significantly during the first week, and marker expression correlated with serum IFN-gamma levels (p less than 0.05); CD14 and HLA class II antigens thereafter returned to pretreatment levels within 4 weeks of therapy despite persistently elevated serum IFN-gamma concentrations. Second, serum neopterin and beta 2-microglobulin concentrations as well as monocyte HLA class I expression also increased significantly within the first week, but remained elevated thereafter without any further dose relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cytokines and lipopolysaccharide on CD14 antigen expression in human monocytes and macrophages

The 52 kD myeloid membrane glycoprotein CD14 represents the receptor for complexes of lipopolysaccharide (LPS) and LPS binding protein (LBP); it is involved in LPS induced tumor necrosis factor-alpha production. Expression of CD14 increases in monocytes differentiating into macrophages, and it is reduced by rIFNg in monocytes in vitro. In the present study CD14 membrane antigen expression was investigated in cultures of human mononuclear leucocytes (PBL), in elutriated, purified monocytes, and in blood monocyte derived Teflon cultured macrophages. Cells were incubated for 15 or 45 h with rIL-1, rIL-2, rIL-3, rIL-5, rIL-6, rTNFa, rGM-CSF, rM-CSF, rTGFb1, rIFNa, lipopolysaccharide (LPS), and, as a control, rIFNg. The monoclonal antibodies Leu-M3 and MEM 18 were used for labelling of CD14 antigen by indirect immunofluorescence and FACS analysis of scatter gated monocytes or macrophages. IFNg concentrations were determined in PBL culture supernatants by ELISA. rIFNa and rIL-2 reduced CD14 in 15 and 45 h PBL cultures, an effect mediated by endogenous IFNg, since it was abolished by simultaneous addition of an anti-IFNg antibody. rIFNa and rIL-2 were ineffective in purified monocytes or macrophages. rIL-4 strongly reduced CD14 in PBL and purified monocytes after 45 h, whereas in macrophages the decrease was weak, although measurable after 15 h. The other cytokines investigated did not change CD14 antigen expression. Cycloheximide alone reduced CD14, but when added in combination with rIFNg the effect on CD14 downregulation was more pronounced. The effect of rIFNg on CD14 in PBL cultures was dose-dependently inhibited by rIL-4 and this inhibition is probably due to an IL-4 mediated blockade of IFNg secretion. LPS at a low dose increased CD14, at a high dose it produced a variable decrease of CD14 in PBL, which was probably due to LPS induced IFNg secretion. LPS strongly enhanced CD14 in 45 h cultures of purified monocytes. The results, showing that CD14 antigen expression is upregulated by LPS and downregulated by rIFNg and rIL-4, suggest that the LPS-LBP receptor is involved in the feedback response of IFNg and IL-4 to LPS stimulation.

Differential HIV replication and HIV-induced interferon production in mononuclear phagocytes: relationship to cell maturation

We have investigated the replication of human immunodeficiency virus (HIV) and HIV-induced interferon (IFN) production in human mononuclear phagocytes at 2 different stages of in vitro maturation. Blood monocytes and monocyte-derived macrophages from 6 healthy, HIV-seronegative donors were challenged with HIV1IIIB and HIV2ROD. Freshly separated monocytes produced IFN when inoculated with both HIV types. In these cultures, an inverse correlation was observed between the amount of IFN production and the rate of HIV replication. In contrast to the monocytes, 5-day-old monocyte-derived macrophages did not produce IFN when challenged with HIV, but a significant replication of HIV1IIIB and HIV2ROD was found in all cultures.

Influence of a muramyl dipeptide on human blood leukocyte functions and their membrane antigens

Murabutide, which belongs to the immunomodulator family of muramyl peptides, was applied directly to fresh human blood to evaluate changes in leukocyte properties. After blood incubation with murabutide, lymphocytes presented a higher responsiveness to T-mitogens, and monocytes and polymorphonuclear cells exhibited an increase in their capacity to produce hydrogen peroxide. In addition, murabutide treatment enhanced phagocytic activity of neutrophils, whereas monocytes presented a decrease in this activity. Some surface markers were also investigated in the distinct leukocyte populations. After incubation with murabutide, a larger number of lymphocytes expressed Ta1 antigen (CD W26) and transferrin receptor (CD 71). In contrast, expression of interleukin-2 receptor (CD 25) was slightly decreased. Monocytes from treated blood displayed a larger number of receptors for C3bi (CD 11b), whereas the surface marker CD 14 and the class I receptor for the Fc portion of IgG were down-regulated. Activation of polymorphonuclear cells by murabutide was confirmed by the up-regulation of the C3bi receptor, Fc receptor, and CD 14 surface antigen. The effects of murabutide on leukocytes described in this paper may contribute to understanding mechanisms of the modulating activity of muramyl peptides on specific and nonspecific immunity.

Human B cells express membrane-bound and soluble forms of the CD14 myeloid antigen

The expression of the myeloid differentiation antigen CD14 on the B lineage was analyzed. A CD14-specific monoclonal antibody was used to isolate the antigen from normal B, B-type chronic lymphocytic leukemia cells, and a representative Epstein-Barr virus-transformed B lymphoblastoid cell line (EBVLCL). A soluble form of this protein was detected in the culture supernatant of all the B cell types tested. The molecule expressed in the normal B and B-type chronic lymphocytic leukemia cells was identical in size to the 52,000 mol. wt monocyte-isolated CD14 glycoprotein. A 64,000 mol. wt antigen was isolated from the lymphoblastoid cell line. Similar 2-D gel electrophoretic patterns to that of the monocyte-derived CD14 were obtained from the normal B and B-type chronic lymphocytic leukemia cell-isolated molecules. These similarities were reflected in minor isoelectric point (pI) differences between the polypeptide spots (pI 4.8), in the first dimension, and identical molecular weight (52,000) in the second dimension. The EBVLCL-isolated polypeptide, when analyzed by 2-D gel electrophoresis, showed a pI identical to that of the myeloid antigen (pI 4.6). The isolated soluble form was of smaller (47,000 mol. wt, normal B and B-type chronic lymphocytic leukemia cells) or similar size (64,000 mol. wt, lymphoblastoid cell line) compared with their corresponding membrane-bound forms. Interestingly, two-colour immunofluorescence analysis showed that only two out of four CD14-specific mAb tested bound to the B cells. We conclude that the CD14 antigen is, in fact, expressed in the B lineage. Its cell surface expression and serum level in the prognosis of B-type chronic lymphocytic leukemia patients needs to be evaluated.

Organization of the monocyte/macrophage system of normal human skin

Monocytes and macrophages are known to be important for a variety of functions; however, whereas epidermal Langerhans cells have been studied in great detail, few data are available for the dermal monocyte/macrophage system. Therefore we investigated the density, distribution, and phenotype of dermal macrophages in normal human skin using a panel of monoclonal antibodies for single and double labeling. We demonstrate here that within normal human dermis macrophages reside with a remarkable density. Principally, these cells exhibit the phenotype of the phagocytic macrophage system (CD11c+, KiM8+), whereas members of the immune phagocyte system (CD11c+, KiM8-) are absent from normal dermis with the exception of a few Langerhans cells in the papillary body. Within the dermal phagocytic macrophage system we uncover an unexpected phenotypical and morphologic heterogeneity, which correlates with the tissue localization. This study provides a basis for investigating the participation and change of the dermal macrophage system in cutaneous disorders.

Recombinant interferon gamma up-regulates in vivo and down-regulates in vitro monocyte CD14 antigen expression in cancer patients

The expression of the monocyte membrane glycoprotein CD14 was measured and related to the serum interferon gamma (IFN gamma) concentration in thirteen patients with disseminated cancer during treatment with human recombinant interferon gamma (rIFN gamma). The drug was administered by continuous subcutaneous infusion using an escalating dose schedule, starting at 50 micrograms/day or 100 micrograms/day and increasing weekly up to 600 micrograms/day, if tolerated. Treatment was continued at a mean maximal tolerated dose of 200 micrograms/day for a median duration of 43 days. Serum IFN gamma concentration and monocyte CD14 antigen expression (immunofluorescence with the monoclonal antibody LeuM3 and fluorescence-activated cell sorting analysis) were determined weekly. The serum IFN gamma concentration was positively correlated with the rIFN gamma dose (P less than 0.05). Therapy induced a dose-dependent enhancement of CD14 antigen expression. The increase in mean CD14 fluorescence intensity was on average 60% after 3 weeks of treatment at a mean dose of 220 micrograms rIFN gamma/day and was reversed after withdrawal of therapy. Patients with a rapidly rising serum IFN gamma concentration (starting dose 100 micrograms/day) showed a smaller increment in CD14 fluorescence intensity than those with slowly rising serum IFN gamma levels (starting dose 50 micrograms/day). Since rIFN gamma is known to down-regulate CD14 antigen expression in vitro, monocytes from patients off therapy and from healthy volunteers were cultured with this cytokine. A similar decrease of CD14 fluorescence was observed in both groups. In patients several factors, such as IFN gamma concentration, duration of drug effect and type of serum, were evaluated and could not explain the discrepant in vivo and in vitro findings. In conclusion, the monocyte marker CD14 was found to be differentially regulated by rIFN gamma in vivo and in vitro. In vivo, secondary mediators, induced by rIFN gamma and acting on a constantly renewed cell population, may contribute to the enhanced CD14 expression.