Variable CD7 expression on T cells in the leukemic phase of cutaneous T cell lymphoma (Sézary syndrome)

CD7, a molecule normally expressed on 90% of normal CD4+ T cells, is often deficient on the malignant T cells of cutaneous T cell lymphoma. To investigate the clinical and biologic implications of CD7 expression, blood lymphocytes from 42 patients with the leukemic phase of cutaneous T cell lymphoma (CD4/CD8 ratio of 10 or more with evidence of a T cell clone in the blood) were analyzed for level of expression of CD7 by flow cytometry. CD7 expression by cells did not clearly segregate into two distinct subgroups that are either CD7 positive or CD7 negative as generally thought; however, nine of 17 patients with a predominantly CD4+CD7+ tumor population on early studies became CD4+CD7- over time whereas the converse situation was not observed. In addition, of three patients with evidence of large tumor cells in the blood coexisting with smaller cells, discordant CD7 expression was observed in one instance. In lymph node specimens, the percentage of cells expressing CD7 and other T cell markers did not correlate with histologic evidence of involvement. CD7 expression on blood lymphocytes also did not correlate with patients' survival nor to serum IgE levels or blood eosinophil counts, a finding suggesting that this marker does not identify functional cell subsets that produce serum interleukin-4 or -5, respectively. We speculate that the level of CD7 expression on malignant T cells may be the effect of sustained antigen stimulation in vivo analogous to what has been proposed to occur with normal T cells during aging.

Fine-needle aspiration biopsy in the evaluation of lymphadenopathy associated with cutaneous T-cell lymphoma (mycosis fungoides/Sézary syndrome)

We studied the role of fine-needle aspiration (FNA) in the evaluation of lymphadenopathy associated with cutaneous T-cell lymphoma (CTCL) in 11 patients with lymphadenopathy and compared findings with corresponding histologic material. Molecular genetic analysis for T-cell clonality by polymerase chain reaction (PCR) was performed on all aspirates. Immunophenotyping was successful in 4 of 7 cases in which flow cytometry was attempted from the aspirated material. Cytologic evaluation of FNA samples correlated strongly with histologic rating of involvement based on numbers of atypical cerebriform lymphocytes in the nodal specimen. Of 7 nodal specimens with scattered or small groups of atypical cells in the background of dermatopathic lymphadenopathy (LN1-2), the cytologic diagnosis was interpreted as reactive in all instances. Of 4 specimens with highly suspect (LN3) or definite histologic involvement (LN4), the cytologic diagnosis was likewise suspect or malignant. The correlation between molecular genetic studies on FNA samples and studies on tissue was not significant; in 2 cases, a T-cell clone was detected in the nodal tissue sample but not in the FNA sample, suggesting undersampling. A T-cell clone was detected by PCR in 5 of 7 nodal specimens judged reactive by FNA biopsy or histologic assessment. FNA for cytologic and molecular genetic analysis is a useful method to evaluate lymphadenopathy associated with CTCL and may obviate the need for surgical biopsy.

Use of serum soluble interleukin-2 receptor levels to monitor the progression of cutaneous T-cell lymphoma

BACKGROUND

The serum concentration of soluble alpha chain of the interleukin-2 receptor (sIL-2R) correlates with tumor burden in cutaneous T-cell lymphoma (CTCL). Therefore the sIL-2R level may be useful to monitor the condition of patients treated with extracorporeal photopheresis or other treatments.

OBJECTIVE

Our goal was to determine the utility of serum sIL-2R as a test in monitoring of patients with advanced CTCL.

METHODS

Serum sIL-2R was measured serially in 36 patients with advanced CTCL treated with extracorporeal photopheresis and other modalities (interferon alfa, methotrexate, topical nitrogen mustard, electron beam).

RESULTS

Serum concentrations of sIL-2R as well as lactate dehydrogenase (LDH) correlated strongly with lymph node size, but only sIL-2R correlated significantly with the severity of skin manifestations in erythrodermic patients. In addition, serum sIL-2R, but not LDH, was significantly higher in patients with nodal involvement. The level of sIL-2R also was significantly higher in patients with large-cell transformation in the skin or lymph nodes compared with patients without transformed disease. During treatment, serum concentrations of both serum sIL-2R and LDH correlated with changes in clinical status, but only sIL-2R showed statistically significant differences in mean levels for different relative global response scores. Pretreatment levels of both sIL-2R and LDH correlated significantly with survival, but only sIL-2R retained significance when both were entered into the Cox proportionate hazards model.

CONCLUSION

The concentration of serum sIL-2R correlates well with disease status and is more useful than LDH or Sézary cell counts to monitor clinical change in patients with advanced CTCL. Moreover, our data suggest that sIL-2R is produced at a relatively low rate by tissue-based lymphoma cells, and that large-cell transformation in CTCL results in marked increase in sIL-2R production in some patients.

Failure of anti-T-cell receptor V beta antibodies to consistently identify a malignant T-cell clone in Sézary syndrome

Monoclonal antibodies (MAbs) reacting with the human T cell receptor (TCR) V beta or V alpha region have been shown to be almost as specific as a private idiotypic MAb in identifying T cell clones. When available, V beta-specific MAbs offer the ease of immunofluorescence analysis to identify and quantitate expanded malignant or nonmalignant T cell populations without requiring polymerase chain reaction (PCR) technology to evaluate expression of V beta gene families. The V beta expression of peripheral blood lymphocytes from twenty-three consecutive patients with Sézary syndrome has been analyzed by reverse transcriptase (RT)-PCR. Ten patients had malignant T cell clones that expressed a TCR V beta corresponding to a commercially available anti-V beta antibody. Immunofluorescence staining with anti-V beta MAbs showed a direct correlation with RT-PCR results in seven of ten patients. No false positive reactivity was noted on immunofluorescence staining with any MAb. Cells from three patients, however, did not react with the corresponding anti-V beta MAb. These three cases expressed a TCR V beta from gene families containing a single member, ie, V beta 14, V beta 18, and V beta 20, yet MAbs reported to be specific for these regions failed to react with the T cell clone from these patients. Sequencing of the PCR product in these cases confirmed the RT-PCR results. Cells from two patients expressed a TCR using V beta 5.1-D beta 1.1 genes with different J-C segments. One patient's cells reacted with an anti-V beta 5.1 MAb (LC4) whereas the other patient's cells bound one-tenth the amount of this same MAb. These results indicate that currently available anti-TCR V region MAbs may not react consistently with T cell clones expressing the corresponding V region or may react with a low affinity making detection difficult. Differences in the J-C junction or in CDR3 may influence the binding of these MAbs. Until the false negative rate is reduced and the fine specificity and affinity of these MAbs is better characterized, both PCR and MAb studies will be required to reliably identify and quantitate clonal T cell populations.

Analysis of p53 and mdm-2 expression in 18 patients with Sézary syndrome

Sézary syndrome is a leukaemic form of cutaneous T-cell lymphoma which presents with multiple cytogenetic abnormalities and responds poorly to chemotherapy. Because of the importance of the p53 tumour suppressor in maintaining genomic stability and in sensitizing transformed cells to DNA damaging agents, we looked for alternations which may affect p53 functions in 18 patients with Sézary syndrome. Cytogenetic analysis suggested frequent p53 gene inactivation since 6/18 patients had loss of one copy of 17p. However, single-strand conformational polymorphism (SSCP) revealed that p53 gene mutations are relatively rare, occurring in only two of 18 Sézary patients. Neither of these two patients was missing a copy of 17p. Possible abnormalities of p53 pathway function through mdm-2 over-expression were also investigated. Although all 18 patients had normal levels of mdm-2 RNA 4/18 over-expressed mdm-2 protein. One patient with advanced disease and the highest percentage of malignant cells overexpressed mdm-2 protein and possessed a nonsense p53 gene mutation. The five patients with abnormalities of p53 or mdm-2 were found to have significantly highest absolute lymphocyte counts and higher absolute numbers of Sézary cells (P=0-021 and 0.027 respectively). In summary, molecular alternations of 17p and potential p53 pathway abnormalities are a common event in Sézary syndrome and appear to be associated with more advanced disease.

Increased serum concentration of the soluble interleukin-2 receptor in cutaneous T-cell lymphoma. Clinical and prognostic implications

BACKGROUND AND DESIGN

The serum concentration of soluble alpha-chain receptor for interleukin-2 (sIL-2R) was determined in 101 patients with cutaneous T-cell lymphoma (CTCL).

RESULTS

The serum concentration of sIL-2R correlates positively with CTCL tumor burden as determined by several clinical parameters (ie, clinical subtype of disease, extent of skin involvement, T rating, and stage), by serum lactate dehydrogenase concentration, and by Sézary cell counts in erythrodermic disease. The median value of sIL-2R in erythrodermic CTCL was more than threefold higher than that of classic mycosis fungoides (MF). The proportion of patients with elevated sIL-2R concentration (> 1000 U/mL) also increased in CTCL in a similar fashion according to the clinical type of disease (MF patch phase, 15%; MF plaque phase, 33%; MF tumor phase, 47%; and erythrodermic variants, 90%). However, no correlation was found between sIL-2R serum concentration and expression of membrane-bound IL-2R alpha chain (CD25) on lymphoid cells in skin lesions and peripheral blood. Significantly, multivariate analysis of various prognostic factors demonstrated that in erythrodermic CTCL, sIL-2R serum concentration correlated best with survival and was a better predictor of prognosis than stage, Sézary cell counts, or lactate dehydrogenase values.

CONCLUSIONS

These findings document the usefulness of the measurement of the sIL-2R serum concentration to determine tumor burden and prognosis in patients with CTCL.

Extracorporeal photopheresis and recombinant interferon alfa 2b in Sezary syndrome. Use of dual marker labeling to monitor therapeutic response

The purpose of this pilot study was to evaluate the role of recombinant interferon alfa 2b (rIFN-a) as adjunct immunomodulatory therapy in patients with Sezary syndrome who were considered unlikely to respond to ExP alone. Six patients were treated with rIFN-a in doses ranging from 3 to 20 million units three times weekly in addition to two consecutive photopheresis treatments every 4 weeks. In addition, to better measure the effect of treatment on circulating neoplastic T-cells, cryopreserved lymphocytes were studied by two-color immunofluorescence and flow cytometry, using anti-CD4 combined with anti-CD29, anti-CD45RA, or anti-CD7. Minimal clinical improvement was observed in 4 patients treated with low doses of rIFN-a (3 to 5 million units TIW), and the response was sustained in only 1 patient. However, a clinically significant and sustained improvement did occur in 1 patient after the dose of rIFN-a was increased (20 million units TIW). Although the encountered toxicity profile from combined ExP/rIFN-a therapy was similar to that expected for ExP or comparable doses of rIFN-a given separately, treatment was discontinued in 2 patients because of adverse effects. Three antibody pairs, i.e., CD4+CD7-, CD4+CD29+, and CD4+CD45RA- subsets, appeared to be useful to monitor changes in blood Sezary cells during treatment. We conclude that the combination of ExP and low doses of rIFN-a does not appear to be effective for patients with advanced Sezary syndrome in this small patient series. However, escalation of interferon dose may be beneficial as shown in one patient, but it cannot be discerned whether the response was due to a combination of therapies, or whether the same therapeutic response would have been achieved with the higher doses of rIFN-a alone. Moreover, while none of the antibody pairs is unique for Sezary cells, the CD4+CD7- subset in appropriate patients provided a good objective measure of response and correlated well with visual Sezary cell counts.

Effect of lovastatin on cell surface expression of Fc receptors or CD14 antigen in human monocytes

Lovastatin is a widely used anticholesterolemic drug which exercises its effect by inhibiting hepatic cholesterol synthesis and up-regulating low density lipoprotein (LDL) receptors. In the present study, we determined that the drug has no adverse effects on the expression of three cell surface antigens of human monocytes, i.e. high affinity Fc receptors (Fc gamma RI), low affinity Fc receptors (Fc gamma RII) and CD14 antigen. We have shown previously these antigens are regulated by cholesterol and lipoproteins. At 0.5 micrograms/mL of culture medium, lovastatin did not reduce the percentage of receptor-positive cells or the average number of receptor molecules per cell. These observations add to the attractiveness of the drug as an anticholesterolemic agent and also indicate that endogenous cholesterol biosynthesis by monocytes is not required for expression of Fc gamma RI, Fc gamma RII, or CD14.

Cholesterol regulates the cell surface expression of glycophospholipid-anchored CD14 antigen on human monocytes

The CD14 antigen which is expressed on human monocytes and macrophages is a phosphatidylinositol-linked surface protein. We investigated the effects of cellular cholesterol depletion and repletion on cell surface expression of this glycoprotein. Adherent normal human monocytes were cultured for four days in media containing delipidated fetal calf serum which depleted cellular cholesterol. Immunofluorescence analysis demonstrated a markedly diminished surface expression of CD14 on cells cultured in delipidated serum compared to normal serum. Expression of CD64 (high-affinity Fc receptors, Fc gamma RI) also was reduced under these conditions. This inhibition of CD14 expression was overcome by addition to the culture medium of cholesterol, low density lipoprotein, or very low density lipoprotein. All of these supplements replenished cellular cholesterol. Expression of CD64(Fc gamma RI) was not restored by addition of cholesterol. These observations indicate that cholesterol can regulate the surface expression of some phosphatidylinositol-anchored glycoproteins.

Influence of HLA genes on T cell receptor V segment frequencies and expression levels in peripheral blood lymphocytes

The effect of the HLA complex on the TCR repertoire in human peripheral blood was assessed by using nine V beta- and V alpha-specific mAb and the quantitative polymerase chain reaction specific for 22 V beta segments. Studies in randomly selected and unrelated individuals failed to show any influence of the HLA complex on the TCR repertoire. In contrast, studies in large families with multiple siblings showed a strong influence on the TCR repertoire by the HLA complex. In pairwise comparisons, HLA-identical sibs had more similar patterns of V segment frequencies, as measured with the nine V segment-specific mAb, as well as more similar expression levels of V beta-specific RNA, as measured by quantitative polymerase chain reaction, than totally mismatched or haplo-identical sibs. When the amount of V beta-specific RNA expressed in CD4+ and CD8+ T cells was compared, it was found that V beta 2, 5.1, 9, and 20 were skewed toward CD4+ T cells; on the other hand, V beta 7 and 14 showed a bias in expression for CD8+ T cells, suggesting that the former were positively selected predominantly by HLA class II gene products whereas the latter V beta segments were positively selected predominantly by HLA class I gene products. These studies unequivocally document the effects of HLA genes on TCR V segment frequencies and expression levels in peripheral blood T lymphocytes.

Influence of HLA genes on T cell receptor V segment frequencies and expression levels in peripheral blood lymphocytes

The effect of the HLA complex on the TCR repertoire in human peripheral blood was assessed by using nine V beta- and V alpha-specific mAb and the quantitative polymerase chain reaction specific for 22 V beta segments. Studies in randomly selected and unrelated individuals failed to show any influence of the HLA complex on the TCR repertoire. In contrast, studies in large families with multiple siblings showed a strong influence on the TCR repertoire by the HLA complex. In pairwise comparisons, HLA-identical sibs had more similar patterns of V segment frequencies, as measured with the nine V segment-specific mAb, as well as more similar expression levels of V beta-specific RNA, as measured by quantitative polymerase chain reaction, than totally mismatched or haplo-identical sibs. When the amount of V beta-specific RNA expressed in CD4+ and CD8+ T cells was compared, it was found that V beta 2, 5.1, 9, and 20 were skewed toward CD4+ T cells; on the other hand, V beta 7 and 14 showed a bias in expression for CD8+ T cells, suggesting that the former were positively selected predominantly by HLA class II gene products whereas the latter V beta segments were positively selected predominantly by HLA class I gene products. These studies unequivocally document the effects of HLA genes on TCR V segment frequencies and expression levels in peripheral blood T lymphocytes.

Lipoproteins upregulate high affinity Fc receptors in human monocytes

Plasma lipoproteins have been implicated in immunoregulation. Here we report that LDL and VLDL up-regulate high affinity Fc receptors (Fc gamma RI) in normal human monocytes. Adherent monocytes were cultured for 4 days in media containing fetal calf serum or delipidated serum. Immunofluorescence analysis showed a significant decrease in percentage of Fc gamma RI-positive cells from 85 +/- 3 in medium containing normal serum to 54 +/- 9 in medium containing delipidated serum. The decrease in the fraction of cells expressing Fc gamma RI was parallel to a decrease in the average number of receptor molecules per cell as indicated by a decrease in the mean value fluorescence intensity from 234 +/- 20 to 112 +/- 14. The inhibition of Fc gamma RI expression was overcome by addition to the culture medium of LDL or VLDL. Since pure cholesterol is ineffective, it is proposed that these lipoproteins deliver a component(s) such as apolipoprotein B-100 which triggers a signal leading to up-regulation of Fc gamma RI in monocytes and macrophages.

Antitumor effects of interleukin-2 and mismatched double-stranded RNA, individually and in combination, against a human malignant melanoma xenograft

The antitumor effects of recombinant interleukin-2 (rIL-2) and mismatched double-stranded RNA (dsRNA) were assessed in tissue culture and in a nude mouse model. Mismatched dsRNA did not show a direct antiproliferative effect against the human malignant melanoma cell line, BRO, in tissue culture. However, treatment of the BRO cells with up to 1000 units/ml rIL-2 in culture showed a slight increase in growth rate. Combined rIL-2/mismatched dsRNA treatment also demonstrated a similar slight enhancement of growth. Nude mice bearing subcutaneous tumors were treated by intraperitoneal injection of low doses (5000-20,000 units) of rIL-2 and mismatched dsRNA (500 micrograms). The in vivo tumor growth was significantly inhibited by the combined treatments (P less than 0.05) and survival was significantly increased (P less than 0.05). Measurement of cytotoxicity using splenocytes from treated animals showed significant augmentation of lytic activity against natural killer (NK)-sensitive YAC-1 cells in all rIL-2/mismatched dsRNA treatment groups, compared to the individual treatments or controls (P less than 0.05). Cytotoxicity of the splenocytes against the NK-resistant BRO cells was also augmented in animals treated with mismatched dsRNA and the highest rIL-2 dose utilized here (P less than 0.01). Renal, liver, and hematological toxicity was evaluated by measurement of blood urea nitrogen, creatinine, serum asparrtate aminotransferase, and a complete blood count with differential. There were no significant differences in these parameters in any of the treatment groups. Similarly, no differences in weight of the animals was seen in any treatment group. These results indicate that the combination of low-dose rIL-2 and mismatched dsRNA can potentiate host-mediated antitumor effects, yielding increased survival, without significant toxicity.

Potentiated lymphokine-activated killer cell activity generated by low-dose interleukin-2 and mismatched double-stranded RNA

Lymphokine-activated killer (LAK) cell activity was measured in human peripheral blood mononuclear cells (PBMC) treated in vitro for 3 days with recombinant interleukin-2 (rIL-2) and mismatched double-stranded RNA (dsRNA). Lytic activity was measured utilizing K562 (NK-sensitive) and 786-0 (NK-resistant) target cells. PBMC cultured with rIL-2 (10-1000 BRMP U/ml) alone showed concentration-dependent lytic activity against the 786-0 target cells, while cells cultured in unsupplemented medium or medium supplemented with mismatched dsRNA (200 micrograms/ml) alone could not lyse the 786-0 targets. The combination of mismatched dsRNA with suboptimal concentrations of rIL-2 (10-30 U/ml) showed enhancement of both natural killer (NK) and LAK cell activities. The uptake of [3H]thymidine by treated effector cells was dependent on time and rIL-2 concentration and was not increased in the cells treated with low-dose rIL-2/mismatched dsRNA, compared to those treated with low-dose rIL-2 or mismatched dsRNA alone. Similarly, changes in the expression of CD3, CD4, CD8, CD57, CD16 and CD25 cell surface antigens were independent or rIL-2 concentration and not altered by the presence of mismatched dsRNA. These results indicate that mismatched dsRNA can potentiate rIL-2-induced LAK cell activity by increasing the functional activity per cell, rather than by increasing the number of activated cells.

Autologous bone marrow transplantation for advanced stage mycosis fungoides

Patients with advanced stage cutaneous T cell lymphoma (CTCL) have a median survival of 2-5 years with no currently available curative therapy. This limited pilot study was performed to determine if CTCL patients could undergo autologous bone marrow transplantation (ABMT) as a curative treatment without developing life-threatening infections. Since selection of a chemotherapeutic regimen is essentially empirical at this time, several drug combinations were screened. Total skin electron beam radiotherapy was used prior to transplantation to control the skin disease of four patients. Six patients have been transplanted and all have engrafted normally. Infections that developed after transplantation responded to conventional therapy and were typical of those observed in other patients undergoing ABMT. Five of the six patients had a complete clinical response to ABMT but three of these responses lasted less than 100 days. Two recent patients who were treated with carmustine, etoposide, and cisplatin are alive more than 1 year after transplantation without evidence of active disease. Thus, although this study does not prove the efficacy of ABMT, it does demonstrate that patients with CTCL can undergo ABMT without developing life-threatening infections and that carmustine-etoposide-cisplatin plus ABMT should be evaluated in subsequent studies to treat patients with poor prognosis CTCL.

Extracorporeal photopheresis in psoriasis vulgaris: clinical and immunologic observations

Four patients with chronic refractory plaque-type psoriasis without arthropathy were treated with extracorporeal photopheresis every other week for 6 to 13 months. In patients 1 and 2, methotrexate was administered concomitantly during the initial part of the trial; the dose was gradually tapered and the drug was discontinued by 6 months. Both patients improved to 23% and 62% of baseline values for percentage of body surface involvement, but their disease then flared when maintenance extracorporeal photopheresis was used alone. Substantial improvement again occurred when lower doses of methotrexate were administered with extracorporeal photopheresis. Patients 3 and 4 were treated initially with extracorporeal photopheresis alone and both improved to 50% and 52% of baseline body surface involvement, respectively, after 4 months of treatment. However, their disease flared because of factors unrelated to treatment. Extracorporeal photopheresis was well tolerated by all patients without evidence of overt toxicity. However, prolonged treatment with extracorporeal photopheresis/methotrexate was accompanied by a decrease in skin reactivity to recall antigens and by decreased capacity of lymphocytes to produce interleukin 2 in response to polyclonal stimuli in vitro. These findings indicate that alternate-week extracorporeal photopheresis has a definite but incomplete suppressive effect on psoriasis vulgaris that may be mediated through an effect on lymphokine production by photomodified cells and that the therapeutic effect of extracorporeal photopheresis may be enhanced by concomitant administration of low doses of methotrexate.

Identification of low density lipoprotein as a regulator of Fc receptor-mediated phagocytosis

Optimal expression of the high-affinity Fc receptor for IgG (FcRI) by the human monocyte cell line U-937 requires the presence of low density lipoprotein (LDL), and neither cholesterol nor high density lipoprotein can provide the component necessary for optimal FcRI expression. Here we show that FcR-mediated phagocytosis also requires LDL. U-937 cells were cultured in medium containing interferon gamma and either fetal calf serum (FCS) or delipidated FCS (DLFCS). The phagocytosis of IgG-coated erythrocytes was measured by a colorimetric assay. U-937 cells cultured in DLFCS medium had less than 16% of the phagocytic activity of cells cultured in normal FCS medium. Phagocytosis of IgG-coated erythrocytes could be inhibited 85% by the addition of murine IgG2a myeloma protein (5 micrograms/ml). U-937 cells cultured in DLFCS medium supplemented with pure cholesterol in ethanol (10 micrograms/ml) had only 30% of the phagocytic activity of cells grown in FCS medium. Addition of very low density lipoprotein (0.2 mg of protein per ml) to DLFCS medium also failed to increase phagocytosis. However, the addition of LDL (0.2 mg of protein per ml) to DLFCS medium restored 90% of the phagocytic activity. Since neither pure cholesterol nor very low density lipoprotein restored normal phagocytic function to U-937 cells despite a normalization of cellular cholesterol content, the restoration of phagocytosis observed with LDL replacement cannot be explained by mere delivery of cholesterol by LDL. Thus, LDL is required for the expression of FcRI and FcR-mediated phagocytosis by U-937 cells and may be an important regulator of phagocytic activity of monocytes and macrophages in vivo.

V beta-specific stimulation of human T cells by staphylococcal toxins

The staphylococcal toxins are responsible for a number of diseases in man and other animals. Many of them have also long been known to be powerful T cell stimulants. They do not, however, stimulate all T cells. On the contrary, each toxin reacts with human T cells bearing particular V beta sequences as part of their receptors for major histocompatibility complex protein-associated antigen. The specificity of these toxins for V beta s puts them in the recently described class of superantigens and may account for the differential sensitivity of different individuals to the toxic effects of these proteins.

Effect of low-density lipoprotein on the expression of high affinity Fc gamma receptors

A substrain of the human monocyte-like cell line U937, which is a cholesterol auxotroph, was used to study the effect of cellular cholesterol depletion on the expression of the type I Fc receptor for IgG (Fc gamma RI). Measurement of Fc gamma RI expression was performed by immunofluorescence and flow cytometry using the monoclonal antibody (mAb) 32.2, which is specific for an epitope on Fc gamma RI, and monomeric IgG2a, which binds to the ligand binding site of Fc gamma RI. Incubation of these cells for 24 h in growth medium containing delipidated fetal calf serum depletes cellular cholesterol without affecting growth or viability. While incubation of U937 cells with human interferon-gamma (IFN-gamma) increased Fc gamma RI expression, cholesterol depletion after cell growth in media containing delipidated serum and IFN-gamma resulted in reduced binding of both mAb 32.2 and IgG2a. A significant decrease in the number of cell surface binding sites, as measured by mean fluorescence intensity, was observed after cholesterol depletion. Supplementation of the delipidated serum medium with pure cholesterol in an ethanol/bovine serum albumin mixture, which replenished cellular cholesterol and supported growth, failed to restore antibody binding significantly. In contrast, low-density lipoprotein (LDL) which also delivered cholesterol to the cells restored binding both in terms of the number of the reactive cells and cell surface receptor density. High-density lipoprotein (HDL3), which does not deliver cholesterol to the cells, showed results similar to those obtained with pure cholesterol. This indicates that either LDL cholesterol is better utilized for membrane synthesis than pure cholesterol or that LDL provides another component, in addition to cholesterol, which is required for expression of Fc gamma RI, but not for growth. These studies indicate a role for LDL in regulating the expression of Fc gamma RI on the cell surface.

Effect of extracorporeal photopheresis on selected immunologic parameters in psoriasis vulgaris

Extracorporeal photopheresis (ExP) was administered every other week in an outpatient setting to four patients with chronic refractory psoriasis vulgaris without arthropathy. The duration of treatment ranged from six to 13 months. Two patients received methotrexate concomitantly during the initial phase of the study. All patients demonstrated a decrease in erythema, induration, and scaling of lesional skin, accompanied by incomplete clearing of lesions such that the percentage of involvement (SI) ranged between 40 to 80 percent of baseline scores. Exacerbations of psoriasis occurred with minor provocations, and two patients who were predisposed to developing epithelial skin neoplasms as a consequence of prior treatments continued to develop tumors during the study interval. Prolonged ExP treatment was otherwise well tolerated, without evidence of toxicity on routine laboratory safety tests or changes in lymphocyte counts. All patients, however, exhibited decreased intradermal skin responses to recall antigens and a decreased capacity of peripheral lymphocytes to produce interleukin 2 (IL-2) in response to polyclonal stimuli in vitro. These observations suggest that the observed anti-inflammatory effect of alternate-week ExP on psoriasis is mediated in part to a direct inhibition of lymphokine production or release by psoralen-ultraviolet-exposed lymphocytes.

S152 (CD27). A modulating disulfide-linked T cell activation antigen

A large subset of normal resting peripheral blood T cells express a protein at low density defined by the murine mAb S152. Reactive T cells are present in both the CD4+ and CD8+ subpopulations. This determinant, however, is not expressed on growth factor-independent T cell lines. After activation of mononuclear cells by either Con A or PHA, greater than 80% of the cells stained at a mean fluorescence intensity that was more than six times that seen on resting cells. When PWM- or mixed lymphocyte reaction-activated cultures were studied, 7 to 22% of S152+ cells stained at high intensity whereas most cells stained at the baseline low intensity. The increased fraction of S152+ cells staining at high intensity after activation paralleled both the increased percentage of anti-Tac+ and 5E9+ cells and cellular proliferation measured by thymidine incorporation. Modulation of the S152 Ag was induced when either Con A- or PHA-activated mononuclear cells were placed into secondary cultures containing S152 mAb. Expression of the S152 Ag began to decrease after 2 h and reached a minimum after 6 h. Resting T cells, however, did not appear to modulate when cultured with S152 mAb. Immunoprecipitation and gel electrophoresis analysis revealed the S152 molecule to have a mobility of 120 kDa before reduction. After reduction the molecule was shown to be composed of two 55-kDa molecules with an isoelectric point of 5 to 6 indicating that the S152 Ag is a disulfide-linked homodimer. These studies confirm that the S152 mAb reacts with the newly defined CD27 molecule. The presence of the S152 Ag on resting and activated cells, its parallel increase with the Tac and 5E9 Ag, and its ability to modulate on activated cells suggest that this molecule may play a functional role during T cell activation.

S152 (CD27). A modulating disulfide-linked T cell activation antigen

A large subset of normal resting peripheral blood T cells express a protein at low density defined by the murine mAb S152. Reactive T cells are present in both the CD4+ and CD8+ subpopulations. This determinant, however, is not expressed on growth factor-independent T cell lines. After activation of mononuclear cells by either Con A or PHA, greater than 80% of the cells stained at a mean fluorescence intensity that was more than six times that seen on resting cells. When PWM- or mixed lymphocyte reaction-activated cultures were studied, 7 to 22% of S152+ cells stained at high intensity whereas most cells stained at the baseline low intensity. The increased fraction of S152+ cells staining at high intensity after activation paralleled both the increased percentage of anti-Tac+ and 5E9+ cells and cellular proliferation measured by thymidine incorporation. Modulation of the S152 Ag was induced when either Con A- or PHA-activated mononuclear cells were placed into secondary cultures containing S152 mAb. Expression of the S152 Ag began to decrease after 2 h and reached a minimum after 6 h. Resting T cells, however, did not appear to modulate when cultured with S152 mAb. Immunoprecipitation and gel electrophoresis analysis revealed the S152 molecule to have a mobility of 120 kDa before reduction. After reduction the molecule was shown to be composed of two 55-kDa molecules with an isoelectric point of 5 to 6 indicating that the S152 Ag is a disulfide-linked homodimer. These studies confirm that the S152 mAb reacts with the newly defined CD27 molecule. The presence of the S152 Ag on resting and activated cells, its parallel increase with the Tac and 5E9 Ag, and its ability to modulate on activated cells suggest that this molecule may play a functional role during T cell activation.

A comparison of low-power helium-cadmium and argon ultraviolet lasers in commercial flow cytometers

The feasibility of installing a low power ultraviolet (UV) laser in a commercial flow cytometer was evaluated by testing an Ortho Cytofluorograf 50HH and a Coulter Epics V. Both instruments were equipped with two argon ion lasers, one emitting at 488 nm and the other in the UV region and were tested by measuring the DNA content of cells stained with Hoechst 33342 or DAPI. The coefficient of variation (CV) of the G0/G1 peak of the DNA histograms produced by each instrument did not deteriorate markedly when results obtained at 100-125 mW were compared to those obtained at 10 mW. These tests indicated that a helium-cadmium laser (He-Cd) which can produce 10 mW at 325 nm should work well as a UV laser in these instruments. An Ortho Cytofluorograf IIs was purchased with a 10 mW He-Cd laser installed in the forward position. Studies of DNA content have confirmed that this low power UV laser can produce CVs of 2.2% with DAPI stained fixed cells and 3.6% with Hoechst 33342 stained viable lymphocytes. Thus, the He-Cd laser should provide a reasonable alternative as a UV source for flow cytometers.

Stimulation of a subset of normal resting T lymphocytes by a monoclonal antibody to a crossreactive determinant of the human T cell antigen receptor

A previous study from this laboratory described a monoclonal antibody, S511, that reacted with the T cell antigen receptor on a human T cell leukemia and also on 1-2% of circulating T lymphocytes in all normal individuals tested. The data presented in the present study demonstrate that, when normal T lymphocytes are cultured with or without irradiated non-T cells in the presence of soluble S511 antibody, a concentration- and time-dependent proliferation of the S511-reactive population occurred. Proliferation indices as high as 184 times greater than control were observed, which represents a major stimulatory effect on the initially minor S511+ subset. When S511+ cells were studied for evidence of prior activation, they were shown to be unresponsive to interleukin 2 (IL-2) unless exposed to S511 antibody, and were shown to be in the G0/G1 phase of the cell cycle. Thus, the S511 antibody activated resting normal T cells in a manner analogous to specific antigen binding to the T cell antigen receptor. The leukemic S511 molecule has been shown previously to differ from most other antigen receptors in the mobility of the two chains at 43 and 38 kD and the neutral isoelectric point of each chain. Expansion of reactive normal cells by S511-Sepharose permitted the development of IL-2-dependent T cell lines enriched for S511-bearing cells. The antigen receptor molecules on one such polyclonal S511-enriched T cell line were immunoprecipitated with S511 antibody and shown to have comparable mobility to that present on the leukemic cells, but to possess a greater heterogeneity of mobility. Thus, the leukemic cells and normal cells express similar T cell receptor molecules. The differences in the S511 T cell antigen receptor molecule possibly relate to differences in glycosylation or polypeptide structure.

T cell antiidiotypic antibodies reveal differences between two human leukemias

Two different human T cell leukemias were compared, using antiidiotype-like murine monoclonal antibodies. In each case these antibodies immunoprecipitated disulfide-linked heterodimer molecules from their respective leukemic cells. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the two idiotype-bearing molecules a major difference in molecular weight was observed, which could be attributed to a similar difference in size of the heavily iodinated chain of either heterodimer. The lightly iodinated chains of both molecules co-migrated at 43 Kd, but appeared to have different isoelectric points on two-dimensional gel analysis. The possibility that these two different heterodimers correspond to different classes of the putative T cell receptor for antigen is discussed. Assays of proliferation of the leukemic cells using Sepharose-bound antiidiotype-like monoclonal antibody showed that one of the leukemic cell types proliferated readily in response to its antiidiotypic antibody. This proliferation was not associated with measurable production of IL-2 and appeared to be a direct effect of the antiidiotypic antibody, which may mimic antigen in its interaction with the T cell receptor for antigen. The other leukemic cell type did not respond to Sepharose-bound antiidiotypic antibody and was generally unresponsive to lymphokines and mitogens. It is possible that the two leukemic cell types represent different stages of T cell differentiation.

Idiotype-like molecules on cells of a human T cell leukemia

Two monoclonal antibodies were obtained that showed unique specificities for the leukemic T cells used for immunization. One antibody, S160, was totally specific for the antigen. The other antibody, S511, also reacted with a small population of normal T cells. This was made especially evident by concentrating these normal T cells with the antibody. Considerable evidence was obtained that both antibodies reacted with the same membrane molecules. In the unreduced state a major component of approximately 80 kdaltons was observed; after reduction this split into two components of approximately 43 and approximately 38 kdaltons. The reaction of the two antibodies with different antigenic sites on the same molecule, one representing a private site and the other a more cross-reactive site, strongly suggests an antibodylike molecule, but composed of polypeptide chains differing from immunoglobulins.

Yersinia enterocolitica lung infection

A 66-year-old man had pneumonia, lung abscesses, and mediastinal adenopathy develop due to Yersinia enterocolitica. There was no evidence of septicemia or acute gastrointestinal disease. Diagnosis was confirmed by cultures of a transtracheal aspirate and sputum. Treatment with cefamandole nafate, which had not been used previously in Y enterocolitica lung disease, resulted in cure.