Armed human monocytes challenged with a sensitizing cancer extract release substances pharmacologically similar to leukotrienes

Allergen-specific leukocyte adherence inhibition (LAI) assay: sensitivity, specificity and mechanism

An allergen-specific tube leukocyte adherence inhibition (LAI) assay has been developed in order to study the mechanism by which leukocytes lose their normal property of adherence to glass. Peripheral blood leukocytes (PBL) from 27 individuals allergic to Dermatophagoides farinae (DF), 10 with seasonal rhinitis not induced by DF and 49 non-allergic healthy volunteers were challenged in vitro with DF and a non-relevant allergen, Artemisia vulgaris (AV) and then assayed for the ability to adhere to glass tubes. Challenge by DF, but not by AV, resulted in loss of adherence by PBL from patients allergic to DF, but not in those of normal controls. The specific LAI response was dose-dependent and occurred only when a critical dose of 0.5 X 10(3) was employed. Following in vitro challenge with DF, radio-immunoassay using an antiserum to LTC4 detected immunoreactive material in supernatants of PBL from DF-allergic individuals. When highly enriched mononuclear cells from non-allergic individuals were armed with cytophilic allergen-specific IgE and challenged with the specific allergen, they lost the property of glass adherence and released a substance that was immunoreactive with LTC4. The results suggest that the chain of events leading to the LAI response in PBL from allergic individuals involves primary recognition of the allergen by specific IgE antibodies bound to receptors on mononuclear cells. The cells are thus triggered to synthesize cysteinyl-containing leukotrienes which mediate the LAI phenomenon. The results suggest that this assay may be used to study allergen-antibody interaction and the subsequent events leading to the clinical picture of atopic diseases.

Leukocyte adherence inhibition in patients with nonmalignant disorders of the colon and colorectal cancer

The tube leukocyte adherence inhibition (LAI) technique was used to investigate the antitumor immunity in two groups of patients generally considered to be at "high risk" of developing colorectal cancer. The first group comprised 21 patients with colorectal polyps and the second 12 patients with various forms of colitis. Also 29 patients with histologically confirmed colorectal cancer were tested. The tube LAI assay was performed using peripheral blood leukocytes from individual patients and crude extracts of colorectal and breast cancers. Positive LAI reactions were observed in 18 out of 29 (62%) patients with colorectal cancer, in 1 out of 21 (5%) patients with colorectal polyps and in 1 out of 12 (8%) patients with colitis. The results indicate that in confirmed cases of malignancies, sensitization to colon tumor-associated antigens could be detected in the tube LAI test, whereas, premalignant sensitization to these antigens in "high risk" groups of patients could not be demonstrated.

Immunological assessment of renal cancer patients as evaluated by the lymphocyte adherence inhibition test

The lymphocyte adherence inhibition test was used to evaluate tumor immunity toward 2 types of soluble renal cancer antigens extracted from 3 different renal cancer specimens. These extractions were accomplished with either 3 molar potassium chloride or 2.5 per cent butanol, and were tested in 23 patients with renal cancer, 8 with benign renal disease and 9 with bladder cancer. In 62 tests of lymphocyte adherence inhibition reactivities toward 3 molar potassium chloride in renal cancer patients the mean value of lymphocyte adherence inhibition reactivity (32.7 +/- 15.4 per cent) was significantly greater compared to that observed in 20 examinations in patients with benign renal disease (17.6 +/- 9.4 per cent, p less than 0.001) and 24 tests in bladder cancer patients (15.4 +/- 4.4 per cent, p less than 0.001). With a lymphocyte adherence inhibition index of greater than 20 per cent as a positive response, there were 50 true positive findings (81 per cent) in the renal cancer group, while the combined benign renal disease and bladder tumor groups had 34 true negative responses (77 per cent). With the butanol extract the mean lymphocyte adherence inhibition reactivity of the 62 tests done on renal cancer patients (38.9 +/- 10.8 per cent) was significantly greater than either control group (7.1 +/- 6.2 per cent, p less than 0.001 for benign renal disease and 5.9 +/- 2.6 per cent, p less than 0.001 for bladder tumor). Moreover, of 62 tests done on renal cancer patients 59 (95 per cent) had true positive responses, while 43 of the 44 tests (98 per cent) in the combined control group showed true negative findings. These results suggest that immune responses in renal cancer can be assessed with the lymphocyte adherence inhibition test, and they may be useful in the diagnosis and management of renal cancer patients.

Mechanism of the LAI test in bladder cancer patients

To clarify the mechanism of the leukocyte adherence inhibition (LAI) test, 30 bladder cancer patients were studied by the fractionated LAI test in which peripheral lymphocytes were separated into monocyte rich and monocyte deplete fractions. The mean LAI reactivity of 30 bladder cancer patients on the monocyte rich fraction (43.2 +/- 20.3 per cent) was significantly higher than that of the corresponding patients on the standard LAI test (30.4 +/- 12.7 per cent), whereas the mean LAI reactivity of these patients on the monocyte deplete fraction (15.6 +/- 10.7%) was significantly lower than that on the standard LAI test of the same patients (respectively p less than 0.001 and p less than 0.01). It suggests that monocytes play an important role in the capillary LAI test. To further comprehend the mechanism of the LAI phenomenon, indicator cells involved in the LAI test were observed by transmission and scanning electron microscopy. The microvilli on the cell surface of nonadherent monocytes of bladder cancer patients were decreased in number and shortened in length but other populations of nonadherent cells were not remarkably changed. These observations showed that the bladder tumor antigens in extracts from tumors appear to have an influence on the microvilli of monocytes, specifically on monocytes from bladder cancer patients. These morphological changes correlate with the results from fractionated LAI assay and may result in the tumor antigen specific LAI reactivity observed in leukocytes of bladder cancer patients.

Leukocyte activation in advanced cancer as an explanation for absent leukocyte adherence inhibition to cancer extracts and chemoattractant

Tube leukocyte adherence inhibition (LAI) measures human immunity by antigen-binding leukocytes releasing chemoattractant-like mediators that are the ultimate inhibitors of adherence by bystander leukocytes. We determined whether the absent LAI responses to cancer extracts for patients with large body burdens of bladder cancer was related to a defect in antigen binding or chemoattractant responsiveness. Leukocytes from patients with small body burdens of bladder cancer gave positive LAI responses of a similar extent to either bladder cancer extracts or chemoattractant [n-formyl-L-methionylleucylphenylalanine (FMLP)]. Of the adherent leukocytes, about 20-30% became non-adherent with a positive LAI response: monocytes, neutrophils and lymphocytes responded. In the control tubes, leukocytes from patients with large body burdens of bladder cancer were more non-adherent and about 15% less adherent than leukocytes from controls or patients with early cancer. They showed no further decrease in adherence, or conversely increase in non-adherence, with either extracts of bladder cancer or FMLP. The leukocytes also failed to transduce transmembrane signals to the same stimuli. The defect was reversible since PGE2 restored the adherence of leukocytes to normal, and subsequently they exhibited membrane potential changes and about 34% non-adherence to either bladder cancer extracts or FMLP. From these results we conclude that chemoattractant LAI-responsive leukocytes from patients with large body burdens of bladder tumor are activated in vivo, probably by mediators from inflammatory cells.

Leukocyte adherence inhibition (LAI) in rats bearing transplantable syngeneic tumors of different immunogenicity

The tube leukocyte adherence inhibition (LAI) assay was used to follow the LAI response in inbred BN rats with subcutaneously (s.c.) transplanted syngeneic liposarcoma (LS175) tumor and in inbred WAG rats with s.c. transplanted syngeneic colon (CC531) and skin (1618) tumors. Initially, the tube LAI assay was used to follow the LAI reactivity of peripheral blood leukocytes (PBL) from BN rats bearing tumor LS175. Sporadic LAI reactivity was observed in the PBL of these rats when incubated with a specific crude tumor extract for either 2 or 20 hr. No definite conclusion regarding the lack of significant tumor-specific LAI reactivity could be drawn since LS175 is a non-immunogenic tumor. Therefore additional LAI studies were performed with the weakly immunogenic tumor CC531 and the highly immunogenic tumor 1618 in WAG rats. Surprisingly, only sporadic LAI reactivity was observed in the PBL of rats bearing either the CC531 or the 1618 tumors using both the 2 and 20 hr LAI assays. This absence of tumor-specific LAI reactivity was particularly remarkable in the highly immunogenic 1618 tumor-bearing rats, since it would suggest that the antigen(s) responsible for its high immunogenicity could not evoke any consistent LAI reactivity. Since oxidative metabolites of arachidonic acid have been shown to be the final mediators of chemoattractant-induced LAI, the adherence inhibition effect of leukotriene B4 (LTB4) on the PBL of BN and WAG rats was also investigated in order to exclude the possibility that the lack of consistent LAI reactivity was due to a lack of responsive cell population in the PBL. PBL of both BN and WAG rats showed a significant increase in the adherence inhibition in the presence of LTB4, suggesting that the sporadic LAI reactivity was not due to a lack of responsive cell population.

Correlation between chemoattractant-induced leukocyte adherence inhibition, macrophage chemotaxis, and macrophage inflammatory responses in vivo

Variations in the magnitude of inflammatory macrophage response in vivo and macrophage chemotaxis in vitro, observed among inbred mouse strains, suggest that these traits are genetically-regulated. The development of an A X B series of recombinant inbred (RI) strains of mice derived from the C57BL/6J (B, high responder) and A/J (A, low responder) resulted in the availability of a large number of new inbred strains which express a spectrum of variations in the magnitude of these traits. These strains were used in the present study as a tool to examine the possible correlation between the phenomenon of leukocyte adherence inhibition (LAI) and those of macrophage inflammatory response in vivo and macrophage chemotaxis in vitro under the assumption the LAI requires the same cellular events as chemotaxis and that LAI resembles, grossly, the accumulation of nonadherent inflammatory cells in vivo. The typing of A X B RI strains for the traits of LAI, macrophage accumulation in vitro, and macrophage inflammatory response in vivo resulted in a correlation between the magnitude of response of those three phenomena in the total of 19 inbred strains tested, thus suggesting that the chemoattractant-induced LAI is biologically related to the events that mediate macrophage chemotaxis in vitro and the macrophage inflammatory response to sterile irritants in vivo.

Purification from a human lung cancer cell line of a water soluble molecule mediating leukocyte adherence inhibition for patients with lung cancer

Soluble lung tumor activity as determined by LAI2 was enriched by physicochemical methods from chemically - defined spent medium of a lung cancer cell line (NCI-H69). To identify the polypeptide carrying the antigenic determinant, splenic lymphocytes of BALB/c mice were immunized with the enriched isolate and hybridized with mouse plasmacytoma cells. Eight hybrids were cloned successfully and produced MAbs that immunoprecipitated principally a single chain of Mr 40,000 (p40) as well as minor chains of Mr 25,000 (p25) and Mr 13,000 (p13) which were probably degradation products of p40. On 2D gels, p40 was composed of 7 spots with a p1 of 6.3 to 7.6, which was not altered by neuraminidase digestion. Affinity chromatography with MAb anti-p40 absorbed p40 and LAI activity. The bound and recovered fraction was enriched for p40 and LAI activity. Affinity-purified p40 also contained the previously identified p25 and p13 as well as a Mr 32,000 peptide (p32). MAb anti-p40 was directed to a common framework determinant on p40 since MAb anti-p40 bound to cancer cells from other organs. The comparatively lung cancer organ-specific determinant recognized by leukocytes from lung cancer patients was not recognized by the MAb. Affinity-purified p40 triggered LAI for leukocytes from patients with lung cancer but not for leukocytes from control subjects or patients with colon cancer or malignant melanoma in rigorous blind testing. Crossreactivity was observed with leukocytes from patients with breast cancer. LAI activity of affinity-purified p40 seems unlikely to result from an unidentified impurity. Thus a p40 molecule has been purified that is expressed on the membranes of lung cancer cells and triggers immunologically-mediated LAI.

Regulation of leukocyte glass adherence and tube leukocyte adherence inhibition (LAI) reactivity by serum factors in dogs with progressing or spontaneously regressing canine transmissible venereal sarcoma (CTVS)

We examined the regulation of leukocyte glass adherence and tube leukocyte adherence inhibition (LAI) reactivity by serum factors in dogs with regressing or progressing canine transmissible venereal sarcomas (CTVS). Both regressor and progressor peripheral blood leukocytes (PBL), draining and non-draining lymph node cells (LNC), and splenic leukocytes were significantly responsive to CTVS antigen extract in tube LAI. In contrast, a significant decrease in basal glass adherence of progressor PBL, draining and non-draining LNC, and splenic leukocytes was observed. Normal glass adherence was restored to progressor leukocytes by extensive washing with warm serum-free media, while significant tube LAI responsiveness to CTVS antigen extract was maintained. Preincubation of regressor PBL and LNC with progressor sera in two-stage tube LAI decreased the basal glass adherence of treated leukocytes. This effect of progressor sera was heat labile, a characteristic of CTVS antigen. Collectively, these findings suggest that progressor leukocytes and progressor sera treated regressor leukocytes were activated by interaction with serum CTVS antigen and thus behaved in tube LAI as stimulated cells, even in the absence of CTVS antigen. Regressor but not progressor sera were shown to contain anti-CTVS IgG with specific arming activity for normal dog PBL, but not LNC in two-stage tube LAI. The nonadherent response of peripheral blood neutrophils in two-stage tube LAI was proportional to the concentration of arming IgG, whereas no change was observed in glass adherence of PBL. The results of this study define the role of progressor and regressor serum factors in the mechanism of tube LAI and demonstrate a relationship between leukocyte glass adherence and the clinical course of CTVS. These findings show that tube LAI is a simple and reproducible measure of active factors in the immune response to a tumor.

Evidence in advanced cancer of an activated leukocyte state to explain the reversible defect in transmembrane signaling and leukocyte adherence inhibition to extracts of cancer

When leukocytes bind tumor antigen, a transmembrane signal induces the cascade of physiological changes that result in leukocyte adherence inhibition (LAI). Leukocytes from patients with early stages of cancer exhibited transmembrane potential (delta psi) changes and LAI when incubated with a cancer extract of the same organ and histogenesis, whereas leukocytes from patients with advanced cancer did not. The refractoriness was reversed by transiently raising intracellular cyclic AMP. LAI is produced by leukotrienes and leukocytes from patients with advanced cancer were refractory to leukotriene-induced delta psi changes which was also restored by raising intracellular cyclic AMP. Moreover, leukocytes could be made refractory to delta psi changes: leukocytes from patients with early cancer when preincubated with a breast cancer extract showed no delta psi change with a second exposure; and leukocytes from control subjects preincubated with leukotrienes showed no delta psi change with a second exposure. The responsive population of leukocytes in LAI to either the specific cancer extract or leukotrienes consisted of about 35 to 42% of the adherent leukocytes. The responsive leukocytes in advanced cancer were already nonadherent, accounting for the 39% increased nonadherence with the control extract. Raising cyclic AMP decreased nonadherence by 39%. The results suggest that leukotrienes and other chemoattractants released in vivo by immune cells binding tumor antigen have stimulated the changes in leukocytes in advanced cancer. However, the unresponsiveness seems to be because of appropriate expression of physiological changes triggered by antigen and chemoattractant stimuli.

Leukotrienes: clinical significance

The leukotrienes, so named because of their initial identification in leukocyte preparations and the presence of three conjugated double bonds (a conjugated triene), are metabolites of the same polyunsaturated fatty acids (e.g., arachidonic acid) that give rise to the prostaglandins, thromboxanes, and several other families of biologically active lipids. Their potential clinical importance derives from their effects on vascular and other smooth muscle reactivity and on leukocyte function. Several leukotrienes may markedly influence the cellular and vascular responses that constitute an integral part of hypersensitivity and inflammatory reactions of the skin. Preliminary data from several laboratories have been presented that implicate a specific leukotriene in the evolution of the lesions of psoriasis.

Transmembrane signal defect and absence of cancer extract induced leukocyte adherence inhibition (LAI) for leukocytes from patients with advanced cancer

Leukocytes from patients with early cancer exhibit leukocyte adherence inhibition (LAI) when incubated with extracts of cancer of the same organ and histogenesis, whereas leukocytes from patients with advanced cancer seldom do. To understand the reason for this refractory state, tumor antigen-induced LAI and transmembrane signalling were measured in the same leukocytes. Transmembrane signalling was measured by changes in membrane potential (delta psi) by the [3H]tetraphenylphosphonium equilibration technique. When leukocytes from patients with early breast cancer were incubated with extracts of breast cancer and malignant melanoma they showed delta psi changes consisting of depolarization and hyperpolarization beginning within 0.5 min after addition of the breast cancer extract and finishing 15 min later. Moreover, they showed no delta psi changes when incubated with extracts of normal breast tissue. Leukocytes from subjects without cancer seldom showed delta psi changes. In criss-cross experiments, leukocytes from patients with melanoma only exhibited delta psi changes when incubated with the melanoma extract. There was a strong correlation between cancer extract-induced delta psi change and LAI. The delta psi change was triggered by leukotriene-like mediators from antibody-dependent monocytes. Authentic leukotrienes triggered delta psi changes in all subpopulation of leukocytes. Leukocytes from patients with advanced breast cancer when incubated with breast cancer extract did not transmit a signal or show LAI. Brief elevation of intracellular cyclic AMP restored both delta psi change and LAI induced by breast cancer extracts, indicating that reactive leukocytes are present but in a refractory state. We conclude that leukocytes from patients with advanced cancer do not react in LAI because tumor antigen does not trigger a transmembrane signal to initiate the cascade of biochemical reactions and physiological changes for LAI.

A study of the immune response to the organ-specific neoantigen of human bladder cancer

The antitumor immune response of monocytes armed with cytophilic antitumor antibody to an organ-specific neoantigen of human bladder cancer was measured by the tube leukocyte adherence inhibition assay. Of 29 patients with Stage A bladder cancer, 27 had positive tests, whereas of 11 patients with Stage B, C and D bladder cancer, 2 had positive tests. If the leukocytes from advanced bladder cancer patients were preincubated briefly with prostaglandin E2, the negative response was converted to positive. Of 189 patients with diseases of other organs, 2 had positive tests. Patients with acute or chronic cystitis had negative tests. The sensitivity of the assay was 88 per cent; specificity was 95 per cent. The bladder cancer extracts prepared from metastatic tissue or the tissue-cultured cell line, T24, had similar activity in the assay. Normal bladder tissue did not share the bladder cancer organ-specific neoantigen nor did cancers of other organs. Bladder epithelial cells expressed the OSN before they acquired invasive properties since patients with dysplastic bladder epithelium or in-situ cancer had positive tests. Antitumor immunity was often detectable before a recurrence became obvious by cystoscopy or cytology of urine and became undetectable quickly after removal of the bladder cancer. Of 100 patients with prior bladder cancer without evidence of exophytic tumor, 18 had positive tests; the possibility must be considered seriously that some had precancerous changes which formed no visible gross abnormalities. The results suggested that antitumor immunity to bladder cancer was a sensitive indicator of precancerous or cancerous changes existing in epithelial cells.