Radiosensitisation of human colorectal cancer cells by ruthenium(II) arene anticancer complexes.

Some of the largest improvements in clinical outcomes for patients with solid cancers observed over the past 3 decades have been from concurrent treatment with chemotherapy and radiotherapy (RT). The lethal effects of RT on cancer cells arise primarily from damage to DNA. Ruthenium (Ru) is a transition metal of the platinum group, with potentially less toxicity than platinum drugs. We postulated that ruthenium-arene complexes are radiosensitisers when used in combination with RT. We screened 14 ruthenium-arene complexes and identified AH54 and AH63 as supra-additive radiosensitisers by clonogenic survival assays and isobologram analyses. Both complexes displayed facial chirality. At clinically relevant doses of RT, radiosensitisation of cancer cells by AH54 and AH63 was p53-dependent. Radiation enhancement ratios for 5-10 micromolar drug concentrations ranged from 1.19 to 1.82. In p53-wildtype cells, both drugs induced significant G2 cell cycle arrest and apoptosis. Colorectal cancer cells deficient in DNA damage repair proteins, EME1 and MUS81, were significantly more sensitive to both agents. Both drugs were active in cancer cell lines displaying acquired resistance to oxaliplatin or cisplatin. Our findings broaden the potential scope for these drugs for use in cancer therapy, including combination with radiotherapy to treat colorectal cancer.

Near infrared photolysis of a Ru polypyridyl complex by upconverting nanoparticles.

NaYF4:Yb(3+)/Er(3+)nanocrystals upconvert near infrared light (980 nm) into higher energy visible photons capable of effecting the photodissociation of the monodentate pyridyl ligand in cis-[Ru(bpy)2(py)2]Cl2: opening an opportunity for advancing the use of photoactivatable metal complexes in medicine and biology.

In vivo tumour and metastasis reduction and in vitro effects on invasion assays of the ruthenium RM175 and osmium AFAP51 organometallics in the mammary cancer model.

We have compared the organometallic arene complexes [(eta(6)-biphenyl)M(ethylenediamine)Cl](+) RM175 (M=Ru(II)) and its isostructural osmium(II) analogue AFAP51 (M=Os(II)) for their ability to induce cell detachment resistance from fibronectin, collagen IV and poly-l-lysine, and cell re-adhesion after treatment, their effects on cell migration and cell viability, on matrix metalloproteinases production, and on primary tumour growth of MCa mammary carcinoma, the effect of human serum albumin on their cytotoxicity. There are differences between ruthenium and osmium. The Os complex is up to 6x more potent than RM175 towards highly-invasive breast MDA-MB-231, human breast MCF-7 and human epithelial HBL-100 cancer cells, but whereas RM175 was active against MCa mammary carcinoma in vivo and caused metastasis reduction, AFAP51 was not. Intriguingly the presence of human serum albumin in the growth medium enhanced the cytotoxicity of both compounds. RM175 increased the resistance of MDA-MB-231 cells to detachment from substrates and both compounds inhibited the production of MMP-2. These data confirm the key role of ruthenium itself in anti-metastatic activity. It will be interesting to explore the activity of osmium arene complexes in other tumour models and the possibility of changing the non-arene ligands to tune the anticancer activity of osmium in vivo.

Investigation of the role of Bax, p21/Waf1 and p53 as determinants of cellular responses in HCT116 colorectal cancer cells exposed to the novel cytotoxic ruthenium(II) organometallic agent, RM175.

Ruthenium(II) organometallic complexes form monofunctional adducts with guanine in DNA in vitro and have a cytotoxic anticancer activity spectrum in preclinical models suggesting lack of cross-resistance with cisplatin. The primary cytotoxic lesion remains to be identified but the downstream mechanism of action is nevertheless of interest. Using isogenic derivatives of the HCT116 colorectal cancer cell line, we investigated the role of p53, p21/WAF1 and Bax in the cellular response to the novel ruthenium(II) organometallic complex RM175, [(eta(6)-C(6)H(5)C(6)H(5))RuCl (H(2)NCH(2)CH(2)NH(2)-N,N')](+) PF(6)(-). Western blotting demonstrated dose-dependent accumulation of p53, Bax and p21/WAF1 within 48 h of the start of RM175 treatment in wild-type HCT116 cells. HCT116 wild-type and Bax-null cells arrested in the G(1) and G(2) phases of the cell cycle. This pattern of cell cycle arrest was not observed in p53-null or in p21/WAF1-null cells. Following RM175 treatment, HCT116 wild-type and p21/WAF1 null cells underwent a dose-dependent induction of apoptosis (Annexin-V and sub-G(1) apoptosis assays). This apoptotic response was not observed in p53-null or Bax-null cells. In short-term sulphorhodamine B assays, the IC(50) for RM175 was 16 microM for p53-null HCT116, and 8 microM for wild-type cells (P<0.05). However, the sensitivity to RM175 in clonogenic assays at 16 days was independent of p53 status. These results identify determinants of the short-term in vitro response to RM175 demonstrating a role for p53 and p21/WAF1 in the growth arrest and for p53 and Bax in the apoptotic response. The mechanism of p53-independent suppression of long-term clonogenicity remains to be determined.

Comparison of the prevalence of inflammatory cells in subtypes of disc herniations and associations with straight leg raising.

STUDY DESIGN: The prevalence of inflammatory cells in 205 disc herniations (DHs) and nine macroscopically normal discs for comparison was studied immunohistochemically. Inflammatory cells were separately analyzed in subtypes of DH. Immunohistochemical data were related to clinical parameters, the straight leg raising test (SLR) in particular. OBJECTIVES: The objectives of the study were to compare the occurrence of inflammatory cells in various subtypes of DH and to determine the association between clinical data and inflammatory cell occurrence in a more extensive sample of DH, with separate analysis of DH subtypes. SUMMARY OF BACKGROUND DATA: Previous studies have suggested a common occurrence of inflammation and inflammatory cells, particularly macrophages, in DHs. No studies on any larger material comprising different subtypes of DH have been done. METHODS: For immunohistochemistry the alkaline phosphatase antialkaline phosphatase method was used. Monoclonal antibodies to T cells in general (CD2), activated T cells (CD25), B cells (CD22), and macrophages (CD68) were used. Obtained immunostaining results were then compared with clinical data, e.g., duration of pain, SLR, and type of DH (sequesters 86, extrusions 103, protrusions 16). Associations were studied by the chi2 test or Fisher's exact test, as applicable (level of significance P < 0.05). RESULTS: Abundant T cells were seen in 17% of the 205 DHs, activated T cells in 17%, B cells in 16%, and macrophages in 37%. All cell types were 2-3 times more prevalent in sequestrated discs than in extrusions. In protrusions macrophages were abundantly seen in 25% (4 of 16) and no other inflammatory cells. In patients with positive SLR and a sequestrated disc abundant lymphocytes were seen three times more often than in extrusions. When patients with bilaterally negative SLR were compared with those with tight SLR (< or =30 degrees ) with respect to inflammatory cell occurrence, some significant differences were noted (CD68, P < 0.025; CD25, P = 0.04). A comparison between SLR bilaterally positive and bilaterally negative also showed associations for all four inflammatory cell types (P = 0.016 to P = 0.029). There was no correlation between inflammatory cells and duration of pain. Abundant inflammatory cells were never seen in control discs. CONCLUSIONS: When SLR was positive and the DH type was sequestered, inflammatory cells were most commonly seen. Our results showed some statistically significant associations between inflammatory cells and SLR, most clearly when comparing bilaterally positive and negative SLR. Interestingly, a bilaterally positive SLR showed an association with all four inflammatory cell types analyzed. Tight SLR also showed an association, particularly with macrophages. In addition to tissue resorption, they may participate in sciatic pain. Even though lymphocytes were less prevalent, they may have some role in sequestered discs and bilaterally positive SLR.

Inflammatory cells, motor weakness, and straight leg raising in transligamentous disc herniations.

STUDY DESIGN: Possible statistically significant relationships between inflammatory cells and either motor weakness or straight leg raising were determined. OBJECTIVES: To look for any clinically relevant links between inflammatory cells in disc herniations and signs of radiculopathy. SUMMARY OF BACKGROUND DATA: Many studies have during recent years shown a presence of various types of inflammatory cells in disc herniations, but their clinical relevance has been questioned. To be clinically relevant, a presence of inflammatory cells should show a clear relationship to clinical evidence of nerve root involvement. Macrophages repeatedly demonstrated in a high proportion of disc herniations studied are of particular interest. Their major role may be in disc herniations tissue resorption and not in sciatica. METHODS: A total of 96 disc herniations, all transligamentous, were analyzed by immunohistochemistry for presence of macrophages, T or B lymphocytes, and activated T lymphocytes separately. From recorded patient data, motor weakness and straight leg raising data were compared with a presence or absence of abundant (+ = at least 20 cells in a group) inflammatory cells. When not abundant, inflammatory cells were classified as "only few cells" (+) and grouped together with "no cells" (-). Patients with or without motor weakness were compared. Straight leg raising was compared for a positive (at <70 degrees ) or a negative test, and separately using the median as cut-off value. Groups were compared by chi-square analysis with the level of statistical significance set at P<0.05. RESULTS: None of the four inflammatory cell types showed any significant association with motor weakness. Nor was any association observed when comparing positive and negative straight leg raising. With the median (straight leg raising = 47.5 degrees ) as cut-off, only activated T cells showed a weak (chi2 = 4.40, P<0.05) relationship with tighter straight leg raising, but none of the other cell types did. Even when straight leg raising was < 47.5 degrees, three times more disc herniations lacked (n = 34) inflammatory cells than showed (n = 13) inflammation. In a subgroup of only sequestrated discs, the findings were similar. However, in the patients with a bilaterally positive straight leg raising (n = 25), the prevalence of at least one inflammatory cell type was much higher in sequestrated discs (80%) than in extrusions (33%). This may suggest more subtle interrelationships between type of disc herniation, straight leg raising, and inflammatory cells. CONCLUSIONS: The results of this study do not support a clinically relevant role for disc herniation inflammatory cells in sciatica. For the cells to be clinically relevant, a strong relationship between a presence of inflammatory cells and either or both of motor weakness and a tight straight leg raising should have been observed. The authors conclude that macrophages, which have been demonstrated in a high proportion of disc herniations in previous studies, are probably more important for disc tissue resorption processes than for producing sciatica. Other types of inflammatory cells are more rarely observed and may have no clinical meaning at all. However, more subtle interrelationships, considering the various types of disc herniations, should be further explored.

The role of mast cells in disc herniation inflammation.

STUDY DESIGN: A study of herniated lumbar disc tissue samples and control disc material to determine the presence of mast cells in disc herniations. OBJECTIVES: To analyze whether mast cells have any involvement in disc herniation pathophysiology and lumbar pain, because mast cells may have an important role in acute and chronic inflammatory responses. SUMMARY OF BACKGROUND DATA: Studies of inflammatory cells, biochemical mediators of inflammation, and tissue degrading enzymes have suggested that these factors may be involved--and perhaps play an important role--in the pathophysiology of lumbar pain and radiculopathy. Mast cells are known to play an important role in acute and chronic inflammatory responses. It was therefore of interest to clarify their possible role in intervertebral disc herniation inflammation. METHODS: Fifty herniated lumbar discs from 50 patients who had undergone disc surgery and three normal control discs were obtained. Sections from every disc then were examined histologically and immunocytochemically for mast cells by using monoclonal antibodies to either of two types of specific proteases of mast cells, tryptase and chymase. RESULTS: By none of the methods could any mast cells be observed in any of the control disc samples. With toluidine blue staining, mast cells were observed in 9 of 50 (18%) of discs. Mast cells immunoreactive to either tryptase or chymase were observed in 10 of 50 disc samples (20%) and immunoreactive for tryptase and chymase simultaneously in 4 of 50 disc samples (8%). However, the majority of the samples studied (80%) demonstrated immunoreactivity to neither tryptase nor chymase. Among the samples studied were five disc protrusions that totally lacked mast cells. CONCLUSIONS: A minority of disc herniations exhibited mast cells, as verified by toluidine blue staining and immunocytochemistry. The results may suggest a role of mast cells in intervertebral disc herniation inflammation, but only in a subset of these cases. Massive infiltration by mast cells never was observed.

DNA interactions of new antitumor aminophosphine platinum(II) complexes.

Mechanistic studies are presented of a novel class of aminophosphine platinum(II) complexes as potential anticancer agents. These new agents, which have demonstrated activity against murine and human tumor cells including those resistant to cisplatin are cis-[PtCl2(Me2N(CH2)3PPh2-P)2] (Com1) and cis-[PtCl(C6H11NH(CH2)2PPh2-N,P)(C6H11NH(CH2) 2PPh2-P)] (Com2). We studied modifications of natural and synthetic DNAs in cell-free media by Com1 and Com2 by various biomedical and biophysical methods and compared the results with those obtained when DNA was modified by cisplatin. The results indicated that Com1 and Com2 coordinated to DNA faster than cisplatin. Bifunctional Com1 formed DNA adducts coordinating to single adenine or guanine residues or by forming cross-links between these residues. In comparison with cisplatin, Com1 formed the adducts more frequently at adenine residues and also formed fewer bidentate lesions. The monofunctional Com2 only formed DNA monodentate adducts at guanine residues. In addition, Com1 terminated DNA synthesis in vitro more efficiently than cisplatin whereas Com2 blocked DNA synthesis only slightly. DNA unwinding studies, measurements of circular dichroism spectra, immunochemical analysis, and studies of the B-Z transition in DNA revealed conformational alterations induced by the adducts of Com1, which were distinctly different from those induced by cisplatin. Com2 had little influence on DNA conformation. It is suggested that the activity profile of aminophosphine platinum(II) complexes, which is different from that of cisplatin and related analogs, might be associated with the specific DNA binding properties of this new class of platinum(II) compounds.

Different coordination modes of a tripod phosphine in gold(i) and silver(i) complexes.

The following gold(I) and silver(I) complexes of the tritertiary phosphine 1,1,1- tris(diphenylphosphinomethyl)ethane, tripod , have been synthesised: Au(3)(tripod)X(3) [X = Cl(1), Br(2), I(3)]; [Au(3)(tripod)(2)Cl(2)]Cl (4); Au(tripod)X [X = Br(5), I(6)]; Ag(3)(tripod) (NO(3))(4) (7), Ag(tripod)NO(3) (8). They were characterized by X-ray diffraction (complexes 2, 3 and 4), (31)P NMR spectroscopy, electrospray and FAB mass spectrometry and infrared spectroscopy. Complexes 2 and 3 show a linear coordination geometry for Au(I), with relatively short Au-P bond distances. Complex 3 has a Au***Au intramolecular distance of 3.326 A degrees , while complex 2 had a short Au***Au intermolecular interaction of 3.048 A degrees . Complexes 4-6 were found by (31)P NMR spectroscopy studies to contain a mixture of species in solution, one of which crystallised as [Au(3)(tripod|)(2)Cl(2)]Cl which was shown by X-ray diffraction to contain both tetrahedral and linear Au(I), the first example of a Au(I) complex containing such a mixture of geometries. The reaction of [Au(3) (tripod)Cl(3)] (1) with tripod led successfully to the formation of [Au(3)(tripod|)(2)Cl(2)](+) and [Au(3)(tripod)(2)Cl(3)](+) and [Au(3)(tripod|)(3)Cl](2+). The silver(I) complexes, 7 and 8 appear to contain linear and tetrahedral Ag(I), respectively.

Comparative immunohistochemical study of group II (synovial-type) and group IV (cytosolic) phospholipases A2 in disc prolapse tissue.

Phospholipase A2 (PLA2) has been suggested to be present in herniated disc tissue and it could possibly be involved in sciatica/ discogenic back pain mechanisms. In the present study the occurrence of two different phospholipase A2 enzymes, (1) low molecular weight (14 kDa) group II synovial-type (sPLA2) and (2) high molecular weight (85 kDa) group IV cytosolic (cPLA2), were compared. Fifty-three disc prolapses obtained at disc operations were analyzed by immunohistochemistry, using anti-human monoclonal antibodies to sPLA2 and cPLA2, respectively. Only cell-associated (disc cells, hyaline cartilage chondrocytes) sPLA2 and cPLA2 immunoreactivity could be observed. The results showed that sPLA2 was more common (25/53, 47%) than cPLA2 (13/53, 25%). sPLA2 and cPLA2 were simultaneously present in 13 of 53 samples (25%). However, both PLA2 enzymes were predominantly present in hyaline cartilage cells (sPLA2: 16/53, cPLA2: 5/53), being less commonly observed in disc cells (sPLA2: 6/53, cPLA2: 3/53). In addition, three samples for sPLA2 and two samples for cPLA2 exhibited immunoreactivity in cartilage and disc cells simultaneously. sPLA2 was observed in no other locations, but in 3 of 53 samples cPLA2 was observed more diffusely in areas of granulation tissue, possibly in macrophages. No gender- or age-related dependence for either type of PLA2 enzyme immunoreactivity could be observed. Neither did their occurrence relate to clinical data such as straight leg raising or neurological deficit. The results do not support a major role for either of the two disc-cell-associated PLA2s in disc pathophysiology. For both enzymes, the major pool appears to reside in cartilage tissue cells, presumably in dislodged end-plate fragments. Disc cells are apparently unlikely candidates for major PLA2 storage.

A comparative immunohistochemical study of inflammatory cells in acute-stage and chronic-stage disc herniations.

STUDY DESIGN: Herniated lumbar disc specimens were obtained from patients undergoing surgical discectomy for persistent radicular pain (radiculopathy) and stained for inflammatory cells to determine their occurrence in relation to the duration of radicular pain and to analyze the role of the time factor in the inflammatory response. OBJECTIVES: To analyze the presence of inflammatory cells and their involvement in the pathophysiology of radicular pain and to determine whether there is a clear difference in the occurrence of inflammatory cells between the earlier phase of radicular pain (after herniation) and the later chronic stage. SUMMARY OF BACKGROUND DATA: Previously, inflammatory cells were reported in herniated disc tissues, and macrophages were most prevalent. Biologically active inflammatory mediators have also been repeatedly observed. However, there have been no observations regarding possible differences in the occurrence of inflammatory cells in radicular pain of different durations. METHODS: Forty-four herniated lumbar discs were obtained from 44 patients undergoing disc surgery. Two groups of 22 age- and gender-matched patients with comparable affected disc levels were studied. In the first group (acute group) pain duration ranged from 3 days to 21 days. In the second group (chronic group) pain duration was 6 months or longer. All disc herniation specimens were subjected to indirect immunocytochemistry to study and compare the presence of inflammatory cells. RESULTS: Inflammatory cells, predominantly macrophages, were observed in both groups. Macrophages were abundantly present in eight (36%) disc samples in the acute group; in three (14%) samples only few scattered macrophages were observed. In the chronic group, in nine (41%) disc samples, abundant macrophages were observed; in six (27%) there were a few scattered macrophages. In the acute group, in three (14%) disc samples abundant activated T lymphocytes were observed; in two (9%) there were only a few activated T lymphocytes, whereas in the chronic group abundant activated T lymphocytes were not seen; only a few scattered activated T lymphocytes were observed in five (23%) disc tissue samples. In two (9%) samples in the acute group, B cells were abundantly present, and in two (9%) only a few B cells were observed. In the chronic group, abundant B cells were seen in no samples, and only a few B cells were noted in one (5%) sample. Only in the acute group and only in lateral disc herniations were abundant lymphocytes observed. In disc samples from intraspinal herniations, acute and chronic, there were only abundant macrophages, not lymphocytes. CONCLUSIONS: Because of the small size of the study groups and the low prevalence particularly of lymphocytes in both groups, no major group differences were noted. The prevalence of macrophages was highest, similar in both groups, and was similar to the results in prior studies. The results indicate no major differences in the occurrence of inflammatory cells in acute and chronic disc herniations. They also indicate that only macrophages may have a clinical relevance in disc tissue inflammation.

Inflammatory cells in full-thickness anulus injury in pigs. An experimental disc herniation animal model.

STUDY DESIGN: Inflammatory cells were studied by indirect immunocytochemistry in experimental full-thickness anulus fibrosus lesions in pigs. OBJECTIVES: First, to determine the occurrence, by immunocytochemistry, of T lymphocytes and macrophages in experimentally produced, anterolateral full-thickness disc lesions in pigs, and second, to compare the presence of inflammatory cells in 1) the injury area, 2) the adjacent noninjured part of the disc, and 3) control discs. SUMMARY OF BACKGROUND DATA: Previous studies on disc herniation material obtained from human disc surgeries have demonstrated inflammatory cells in a subgroup of herniations. Macrophages were most prevalent, being more numerous than lymphocytes. Macrophages have furthermore been suggested to be important in the resorption process of extruded disc tissue. No similar studies on an animal model of disc herniation, however, have so far been presented. METHODS: A full thickness anular incision, 10 mm long, was made with a scalpel in the L3-L4 or L4-L5 intervertebral discs of 12 adult pigs. The incision was made in the anterolateral part of the disc. Nucleus material was observed outside the injury site when tissue samples were taken, suggesting a disc herniation. Tissue then was analyzed from the area of injury, from the area adjacent to the injury, and from separate control discs from three additional pigs of the same age. Thin frozen sections were studied by indirect immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase method) using monoclonal anti-human antibodies applicable to porcine tissues, T lymphocytes (CD3), and macrophages (CD68). Cells were graded as: -, absent; (+), only a few scattered cells; and +, abundant cells. Disc tissue samples were taken 1 month (three discs), 2 months (four discs), and 3 months (five discs) after the operation. RESULTS: Macrophages were present more commonly than T cells, and were abundant in seven of 12 discs (58%), with T cells abundant in four of 12 discs (33%). Only a few macrophages were present in the injured tissue from one additional disc, and scattered T cells were seen in four additional discs. Abundant macrophages were also observed in one of two discs in the adjacent noninjured area, whereas only a few T lymphocytes at the most were present in such noninjured disc tissue. In four (33%) and three (25%) injured discs, respectively, no macrophages or T lymphocytes could be found. No inflammatory cells were observed in three of 12 discs (25%). The three control discs showed no inflammatory cells. CONCLUSIONS: Inflammatory cells, predominantly macrophages, were present in a subsample of experimental discs with full-thickness anulus defects, as has previously been observed for human disc herniations. In this animal model, macrophages may have spread to adjacent noninjured parts of the disc. The induced herniation in this animal model is, however, anterolateral and may not fully correspond to clinical disc herniations, most of which are posterolateral. However, the results from this model support a role for inflammation in disc herniation.

Inflammatory cells in experimental intervertebral disc injury.

STUDY DESIGN: Inflammatory cells were located by immunocytochemistry in areas of experimental intervertebral disc injury in pigs. OBJECTIVES: To study the occurrence of T lymphocytes and macrophages 1 week, 1 month, and 3 months after partial-thickness transverse scalpel injuries in pig lumbar discs. SUMMARY OF BACKGROUND DATA: Inflammatory cells and mediators recently have been observed in disc herniation tissue that was removed at disc prolapse surgery. The prevalence of inflammatory cell infiltrates in such clinical disc tissue material also has been studied. There are no studies, however, that have analyzed, using immunocytochemical methodology, the occurrence of, types of, and time dependence of inflammatory cells in an experimental disc injury model. The role of inflammation in intervertebral disc injury and repair has not been determined. METHODS: Transverse scalpel injuries 5-mm long and 4-mm deep were cut in the anterolateral anulus of L5-L6 and L4-L5 discs in 16 pigs. The cuts in the center of the anulus did not reach the nucleus pulposus and never produced a disc prolapse. In every pig, two non-adjacent lumbar discs (L1-L2 and L2-L3) were used as controls. Four discs per animal were studied in parallel by two different complementary immunohistochemical staining protocols. T lymphocytes and macrophages were located immunohistochemically using CD3 and CD68 antibodies, respectively. Discs were removed for analysis from four pigs at 1 week, from six pigs at 1 month, and from six pigs at 3 months. Inflammatory cells were categorized by two independent observers as being entirely absent (-), only few scattered cells (+), and at least one larger cellular infiltrate (+2). RESULTS: In none of the discs could extensive inflammatory cell infiltration be observed. T lymphocytes were present in significantly more sections cut from injured discs than in sections cut from control discs. The difference was highly significant particularly at 1 week and 1 month after disc removal. Only the 1-month-after-injury sections from injured discs exhibited significantly more macrophages than those from control discs. CONCLUSIONS: The results suggest the presence of only modest inflammatory cell infiltration in experimental intervertebral disc injury at all follow-up times. The inflammatory response in partial-thickness anterior experimental intervertebral disc injury, in the absence of disc prolapse, seems to be dominated by a T lymphocyte response. The macrophage response is apparently strongest at 1 month after such injury. These findings differ from what has been observed in herniated disc tissue.

Immunocytochemical localization of immunoglobulins in disc herniations.

STUDY DESIGN: Disc herniation and control discs were studied for the presence of immunoglobulins immunocytochemically. OBJECTIVES: To study a possible presence of immunoglobulin complexes in herniated disc tissue and to locate them at the tissue level by immunocytochemistry; to compare immunohistologic findings with those obtained in control disc tissue; and to compare the prevalences of immunoglobulin M and immunoglobulin G. SUMMARY OF BACKGROUND DATA: In herniated disc tissue, high activity of inflammatory phospholipase A2 was previously demonstrated, and inflammatory cells were noted immunohistochemically. Immunoglobulins G and M were observed biochemically but have not been located at the tissue level. METHODS: Fifty-two disc herniations and three macroscopically normal fresh cadaver discs were managed by an identical immunocytochemical protocol, using monoclonal antihuman antibodies to immunoglobulins M and G. RESULTS: In 29 of 52 disc herniations (56%), immunoglobulin M deposits were observed, and in 18 of 52 disc herniations (35%) immunoglobulin G could be demonstrated. Almost all the disc herniations where immunoglobulin G was present also contained immunoglobulin M deposits (except for two). In the control discs studied, neither immunoglobulin could be observed immunohistochemically. The immunoglobulin deposits were noted in areas where blood vessels were also present. Morphologically, immunoglobulin immunoreactivity resembling immune complexes was observed. CONCLUSIONS: The results lend support to previous suggestions of inflammation and immune reaction in disc herniations, including previous biochemical studies suggesting immunoglobulin deposition. The exact role of the demonstrated immunoglobulins in disc tissue pathophysiology will have to be clarified further.