Prevention of alterations in postoperative lymphocyte subpopulations by cimetidine and ibuprofen

Histamine type 2 receptor antagonists as adjuvant treatment for resected colorectal cancer

BACKGROUND

Anecdotal reports of tumour regression with histamine type 2 receptor antagonists (H(2)RAs) have lead to a series of trials with this class of drug as adjuvant therapy to try and improve outcomes in patients with resected colorectal cancers. There was a plausible scientific rationale suggesting merit in this strategy. This included improved immune surveillance (by way of increasing tumour infiltrating lymphocytes), inhibiting the direct proliferative effect of histamine as a growth factor for colorectal cancer and, in the case of cimetidine, inhibiting endothelial expression of E-selectin (a cell adhesion molecule thought to be critical for metastatic spread).

OBJECTIVES

To determine if H(2)RAs improve overall survival when used as pre- and/or postoperative therapy in colorectal cancer patients who have had surgical resection with curative intent. We also stratified the results to see if there was an improvement in overall survival in terms of the specific H(2)RA used.

SEARCH METHODS

Randomised controlled trials were identified using a sensitive search strategy in the following databases: MEDLINE (1964 to present), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2009), EMBASE (1980 to present) and Cancerlit (1983 to present).

SELECTION CRITERIA

Criteria for study selection included: patients with colorectal cancer surgically resected with curative intent; H(2)RAs used i) at any dose, ii) for any length of time, iii) with any other treatment modality and iv) in the pre-, peri- or post-operative period. The results were stratified for the H(2)RA used.

DATA COLLECTION AND ANALYSIS

The literature search retrieved 142 articles. There were six studies included in the final analysis, published from 1995 to 2007, including a total of 1229 patients. All patients were analysed by intention to treat according to their initial allocation. Log hazard ratios and standard errors of treatment effects (on overall survival) were calculated using the Cochrane statistical package RevMan Version 5. Hazard ratios and standard errors were recorded from trial publications or, if not provided, were estimated from published actuarial survival curves using a spreadsheet designed for this purpose (http://www.biomedcentral.com/content/supplementary/1745-6215-8-16-S1.xls).

MAIN RESULTS

Of the six identified trials, five used cimetidine as the experimental H(2)RA, whereas one used ranitidine. There was a trend towards improved survival when H(2)RAs were utilised as adjuvant therapy in patients having curative-intent surgery for colorectal cancer (HR 0.70; 95% CI 0.48-1.03, P = 0.07). Analysis of the five cimetidine trials (n = 421) revealed a statistically significant improvement in overall survival (HR 0.53; 95% CI 0.32 to 0.87).

AUTHORS' CONCLUSIONS

Of the H(2)RAs evaluated cimetidine appears to confer a survival benefit when given as an adjunct to curative surgical resection of colorectal cancers. The trial designs were heterogeneous and adjuvant therapy has evolved since these trials were performed. Further prospective randomised studies are warranted.

Cimetidine inhibits salivary gland tumor cell adhesion to neural cells and induces apoptosis by blocking NCAM expression

Background

Cimetidine, a histamine type-2 receptor antagonist, has been reported to inhibit the growth of glandular tumors such as colorectal cancer, however the mechanism of action underlying this effect is unknown. Adenoid cystic carcinoma is well known as a malignant salivary gland tumor which preferentially invades neural tissues. We demonstrated previously that human salivary gland tumor (HSG) cells spontaneously express neural cell adhesion molecule (NCAM), that HSG cell proliferation may be controlled via a homophilic (NCAM-NCAM) binding mechanism and that NCAM may be associated with perineural invasion by malignant salivary gland tumors. We further demonstrated that cimetidine inhibited NCAM expression and induced apoptosis in HSG cells. Here, we investigated the effects of cimetidine on growth and perineural/neural invasion of salivary gland tumor cells.

Methods

In this study, we have examined the effect of cimetidine on cancer cell adhesion to neural cells in vitro, one of the critical steps of cancer invasion and metastasis. We have also used an in vivo carcinogenesis model to confirm the effect of cimetidine.

Results

We have demonstrated for the first time that cimetidine can block the adhesion of HSG cells to neural cell monolayers and that it can also induce significant apoptosis in the tumor mass in a nude mouse model. We also demonstrated that these apoptotic effects of cimetidine might occur through down-regulation of the cell surface expression of NCAM on HSG cells. Cimetidine-mediated down-regulation of NCAM involved suppression of the nuclear translocation of NF-κB, a transcriptional activator of NCAM gene expression.

Conclusion

These findings suggest that growth and perineural/neural invasion of salivary gland tumors can be blocked by administration of cimetidine via induction of apoptosis and in which NCAM plays a role.

Positive correlation between sialyl Lewis X expression and pathologic findings in renal cell carcinoma

BACKGROUND

Interaction between tumor cells and endothelium plays a major role in cancer invasion and metastasis. Among various cell adhesion molecules, the cognate interaction between sialyl Lewis antigen expressed in the tumor cell surface and E-selectin expressed on endothelial cells is considered to be crucial for the tumor cell adhesion to the endothelium.

METHODS

The sialyl Lewis X (sL(X)) expression in 45 specimens from renal cell carcinoma patients was examined using immunohistochemistry.

RESULTS

In this study, we demonstrate that the immunoreactivity for sL(X) in renal cell carcinoma specimens not only correlates with conventional histopathologic parameters but also serves as a useful indicator for the prognosis of renal cell carcinoma.

CONCLUSION

Since beneficial effect of cimetidine has been reported and ascribed to its inhibitory action on the expression of E-selectin, a ligand molecule of sialyl Lewis antigen, cimetidine may also show inhibitory effect on the tumor recurrence and metastasis of renal cell carcinoma with high level of sL(X) expression.

Effects of Preinjury Administration of Corticosteroids on Pseudointimal Hyperplasia and Cytokine Response in a Rat Model of Balloon Aortic Injury

Restenosis occurs in approximately one-third of patients with coronary or peripheral vascular disease who undergo balloon angioplasty or a surgical bypass procedure primarily because of the development of pseudointimal hyperplasia (PIH). Corticosteroids were effective in suppressing PIH in several experimental studies, but no clinical studies have been reported. To resolve this discrepancy, we studied the effects of preinjury administration of several doses of methylprednisolone (MP) at targeted times in a rat model of balloon aortic injury. Rats were given either no treatment or an intravenous injection of MP (0.5, 5.0, 50, or 500 mg/kg) 2 hours before aortic injury. Four hours later interleukin-6 (IL-6), IL-10, and macrophage migration inhibitory factor (MIF) concentrations in serum and tissue of injured aortas were assessed. Two weeks after injury, damaged aortas were harvested and studied histopathologically. Compared with results in controls, MP at a dose of 5 mg/kg significantly inhibited increases in plasma and tissue levels of IL-6 and significantly reduced the pseudointimal area, pseudointimal/medial area ratio, and proliferating cell nuclear antigen index in injured vessels. Administration of MP had no significant effect on the IL-10 or MIF level. Thus in a rat model of balloon aortic injury, preinjury administration of MP 5 mg/kg mitigated the development of PIH and cell proliferation and suppressed the postinjury increase in serum and tissue IL-6 concentrations. These results suggest that there is an appropriate dosage as well as appropriate timing for MP administration to suppress PIH.

Perioperative cimetidine administration promotes peripheral blood lymphocytes and tumor infiltrating lymphocytes in patients with gastrointestinal cancer: Results of a randomized controlled clinical trial

AIM: To study the effects of perioperative administration of cimetidine (CIM) on peripheral blood lymphocytes, natural killer (NK) cells and tumor infiltrating lymphocytes (TIL) in patients with gastrointestinal (GI) cancer.

METHODS: Forty-nine GI cancer patients were randomized into treatment group, who took CIM in perioperative period, and control group, who did not take the drug. The treatment was initiated 7 days before operation and continued for 10 days after surgery. At baseline examination before operation, on the 2nd and 10th postoperative days, total T lymphocytes, T helper cells, T suppressor cells, and NK cells in peripheral blood were measured respectively by immunocytochemical method using mouse-anti human CD₃, CD₄, CD₈ and CD₅₇ monoclonal antibodies. Blood samples from 20 healthy volunteers were treated in the same way as normal controls. Surgical specimens were examined during routine histopathological evaluation for the presence of TIL in tumor margin. Immunohistochemical study was performed to measure the proportion of T and B lymphocytes in TIL population. T and B lymphocytes were detected respectively using mouse-anti-human CD₃ and CD₂₀ monoclonal antibodies.

RESULTS: In comparison with normal controls, both the treatment and control groups had decreased T cells, T helper cells and NK cells at baseline. In control group, total T cells, T helper cells and NK cells declined continuously with the disease progression and the decrease became more obvious after operation. From baseline to the 2nd postoperative day, the proportion of total T cells, T helper cells, and NK cells went down from 60.5 ± 4.6% to 56.2 ± 3.8%, 33.4 ± 3.7% to 28.1 ± 3.4%, and 15.0 ± 2.8% to 14.2 ± 2.2%, respectively. On the other hand, there were significant improvements in these parameters after CIM treatment. On the 10th postoperative day, the treatment group had significantly higher percentages of total T cells, T helper cells and NK cells than control group. Moreover, CIM treatment also boosted TIL response, as was reflected by findings that 68%(17/25) of the patients in treatment group had significant TIL responses and only 25% (6/24) of the cases had discernible TIL responses (P < 0.01).

CONCLUSION: Perioperative application of CIM to GI cancer patients could help restore the diminished cellular immunity induced by tumor burden and surgical maneuver. The drug could also boost TIL responses to tumor. These effects suggest that the drug be used as an immunomodulator for GI cancer patients.

Cimetidine prevents suppression of delayed hypersensitivity in an animal model of haemorrhagic shock

BACKGROUND

Cimetidine reverses immunosuppression following trauma, however, its effect on pure haemorrhagic shock is unknown.

METHODS

Mice sensitized by injection of sheep red blood cells (SRBCs), were subjected to cardiac puncture and randomized to a control group-A (n=11) and three shock groups (35% of blood volume extracted): group-S had no treatment (n=16), group-CP received cimetidine 50mg/kg intraperitoneally (n=16), group-CW received oral cimetidine (200mg/kg per day, n=16). After 5 days, animals were challenged by injection of SRBCs into the foot-pad of the right hind paw (same volume of saline was injected into left paw). Foot-pad thickness ratios (FPTRs) were determined at 16 and 40 h, and inflammatory response was assessed histologically.

RESULTS

At 16 h, FPTRs were greater in group-CW than group-S (P=0.01). There were no differences at 40 h. More animals in groups-CP and -CW had grade 3/4 inflammation, whilst group-S had the least inflammatory response (NS).

CONCLUSIONS

Cimetidine prevents suppression of delayed hypersensitivity in this model.

Cimetidine increases survival of colorectal cancer patients with high levels of sialyl Lewis-X and sialyl Lewis-A epitope expression on tumour cells

Cimetidine has been shown to have beneficial effects in colorectal cancer patients. In this study, a total of 64 colorectal cancer patients who received curative operation were examined for the effects of cimetidine treatment on survival and recurrence. The cimetidine group was given 800 mg day(-1) of cimetidine orally together with 200 mg day(-1) of 5-fluorouracil, while the control group received 5-fluorouracil alone. The treatment was initiated 2 weeks after the operation and terminated after 1 year. Robust beneficial effects of cimetidine were noted: the 10-year survival rate of the cimetidine group was 84.6% whereas that of control group was 49.8% (P<0.0001). According to our previous observations that cimetidine blocked the expression of E-selectin on vascular endothelium and inhibited the adhesion of cancer cells to the endothelium, we have further stratified the patients according to the expression levels of sialyl Lewis antigens X (sL(x)) and A (sL(a)). We found that cimetidine treatment was particularly effective in patients whose tumour had higher sL(x) and sL(a) antigen levels. For example, the 10-year cumulative survival rate of the cimetidine group with higher CSLEX staining, recognizing sL(x), of tumours was 95.5%, whereas that of control group was 35.1% (P=0.0001). In contrast, in the group of patients with no or low levels CSLEX staining, cimetidine did not show significant beneficial effect (the 10-year survival rate of the cimetidine group was 70.0% and that of control group was 85.7% (P=n.s.)). These results clearly indicate that cimetidine treatment dramatically improved survival in colorectal cancer patients with tumour cells expressing high levels of sL(x) and sL(a).

Effect of cimetidine on intratumoral cytokine expression in an experimental tumor

To evaluate the immunomodulatory effects of histamine in vivo, we analyzed an experimental syngenic tumor model using a colon adenocarcinoma cell line, CT-26, in Balb/c mice. In this model, distinct tumor growth was observed around 6 days after inoculation. Daily administration of cimetidine (0.12 mg/kg/day) significantly suppressed the increases in tumor volume and weight. On day 6 and day 7, histidine decarboxylase (HDC) activity was markedly increased. To examine the alterations in the local immune system, the cytokine expressions in the tumor tissue were measured by ribonuclease protection assay. The cytokine expression levels such as lymphotoxin-beta, tumor necrosis factor-alpha, interferon-gamma, interleukin-10, and interleukin-15 were considerably lower in tissues on day 14 than those on day 6. These decreased expressions were all restored by cimetidine. These results indicated that the effects of cimetidine on tumor growth in this model might be mediated by restoration of the decreased local cytokine expression, which exerts antitumoral effects.

Laparoscopic-assisted vs. open surgery for colorectal cancer: comparative study of immune effects

PURPOSE

Our aim was to test the hypothesis that laparoscopic-assisted resection for colorectal cancer has an immunologic advantage over traditional open surgery.

METHODS

Sixteen patients with colorectal cancer were randomized to undergo laparoscopic-assisted resection or open surgery. Basic patient data were recorded, and serum interleukin-6 levels, relative proportions of lymphocytes, and human leukocyte antigen-DR expression on monocytes were determined at specific time intervals.

RESULTS

Operating time was longer for laparoscopic-assisted resection (P=0.02), but analgesic requirements were less (P=0.04). All patients exhibited the following: interleukin-6 levels increased to a maximum at 4 hours and returned to preoperative levels within 48 hours. This response appeared greater for open resection (mean peak level, 313 vs. 173 pg/ml; P=0.25). Relative granulocytosis (P < 0.001) was seen within 48 hours, which was offset by a decrease in percentage of lymphocytes (P < 0.001). Changes in lymphocyte subfractions were most significant seven days postsurgery: natural killer cells decreased (P=0.003); T cells increased (P=0.008), with elevation in the CD4/CD8 ratio (P=0.003). B cells were largely unchanged at all time periods. Human leukocyte antigen-DR expression on monocytes was significantly less at 48 hours postsurgery (P < 0.001). All changes were reversed within three weeks of surgery. There were no differences when comparing laparoscopic-assisted resection with open surgery.

CONCLUSIONS

Both laparoscopic-assisted resection and open surgery affect the immune response. It would appear that laparoscopic-assisted resection does not have an immunologic advantage over open surgery in patients with colorectal cancer.

Pilot study--cimetidine enhances lymphocyte infiltration of human colorectal carcinoma: results of a small randomized control trial

BACKGROUND

Cimetidine preserves postoperative immune function and inhibits the growth of some cancers. In this study, the effect of cimetidine on the local immune response to colorectal carcinoma was investigated.

METHODS

Forty-two patients scheduled for elective resection of colorectal carcinoma were randomized either to receive cimetidine for 1 week perioperatively or to act as controls. A lymphocyte density of 50 cells per high-power field (approximately 50% of the tumor/tissue interface) was considered a positive response. Patient survival was determined by Kaplan-Meier life table analysis. The effects of histamine and cimetidine on normal subject lymphocyte function was determined in a mitogen-stimulated proliferation assay.

RESULTS

A positive lymphocyte response was observed in 5 of 24 control carcinoma patients (21%) and 10 of 18 cimetidine-treated carcinoma patients (56%) (P = 0.03). The presence of a lymphocyte response correlated with a better survival (P = 0.02). Histamine had an inhibitory effect on lymphocyte proliferation with a median effective dose of 5 x 10(-7) M. Cimetidine antagonized this effect with a negative logarithm of the cimetidine molar concentration required to reduce the effect of histamine in half of 6.55.

CONCLUSIONS

Histamine inhibits normal lymphocyte function, antagonized by cimetidine at a histamine type 2 receptor. Cimetidine increases lymphocyte infiltration of primary colorectal carcinoma, possibly by overcoming the immunosuppressive effects of high local histamine concentrations. The presence of a local lymphocyte response correlates with an improved 3-year survival.

Immunoregulatory effects of indomethacin on rats with trauma

In this article, we investigated changes of immune functions and immunoregulatory effects of indomethacin on rats with trauma. The results show that spontaneous suppressor T cell activity of spleen significantly increased and Interleukin I production and DNA synthesis capacity of splenocytes markedly decreased in rats with trauma. Indomethacin could markedly improve immune function, decreased spontaneous suppressor T cell activity and prompted Interleukin 2 production and DNA synthesis capacity of splenocytes.

Cimetidine as an adjuvant treatment in colorectal cancer. A double-blind, randomized pilot study

PURPOSE

To evaluate the influence of a H2 receptor antagonist (cimetidine) on survival in patients with colorectal carcinoma, a randomized, controlled pilot study was performed in three university hospitals in Copenhagen, Denmark.

METHODS

A total of 192 patients, who had undergone a resection or an exploratory operation for adenocarcinoma of the colon or rectum between May 1988 and May 1991, were enrolled in the study. After a median observation time of 40 months, outcome was noted for each patient concerning cancer-specific mortality rate.

RESULTS

In patients operated with curative intent (n = 148), no difference was found in cancer-specific mortality between the two treatments. However, a tendency toward reduction in mortality rate was found in patients with curatively operated Dukes Stage C carcinoma (P = 0.11, log-rank test; difference, 29 percent; 90 percent confidence interval, 2 to 57 percent) in the cimetidine-treated group. In patients with disseminated disease no total difference was found between the two treatment groups.

CONCLUSIONS

Cimetidine does not seem to reduce mortality in patients with colorectal cancer, but there seems to be a tendency toward a survival benefit in patients undergoing surgery for Dukes Stage C carcinoma. Results seem to justify trials in this patient category to reveal a benefit of H2 receptor antagonists in adjuvant therapy of colorectal carcinoma.

Cimetidine preserves non-specific immune function after colonic resection for cancer

Fifty consecutive patients undergoing resection of colorectal cancer were randomized to either receive cimetidine at a dose of 400 mg bd for a minimum of 5 pre-operative days, then intravenously for 2 postoperative days, or to act as controls. Baseline immune function was determined in all patients by in vitro testing of lymphocyte proliferation (LP) in response to mitogen, skin testing for cell mediated immunity (CMI) and measurement of lymphocyte subsets. Immune function was retested in both groups on the second postoperative day. In control patients the mean postoperative LP value was 41% of pre-operative levels (P < 0.0001) and the mean CMI reduced to 29% (P < 0.0001). Patients treated with cimetidine had no significant fall in these parameters. Numbers of T and natural killer (NK) cells fell after surgery in both groups, and B cell numbers were maintained in the cimetidine group. It is concluded that cimetidine reduces the immunosuppression that follows colonic resection.

Elevation of circulating interleukin 6 after surgery: factors influencing the serum level

To investigate the effect of surgical trauma and other factors on the postoperative elevation of serum interleukin 6 (IL-6), we examined changes in IL-6 concentration after major thoracoabdominal surgery. Serum IL-6 levels reached the maximum concentration on the first postoperative day in all 38 patients, with peak ranging from 1400.8 +/- 383.4 pg/ml (mean +/- SEM) to 29.8 +/- 3.8 among six groups who underwent surgery at different sites. The IL-6 peak was significantly correlated with surgical trauma as defined by the operation length and the volume of blood loss during surgery (r = 0.554, P < 0.01 and r = 0.427, P < 0.01, respectively). The peak concentration of serum IL-6 in patients undergoing esophagectomy was significantly higher than in those undergoing pancreaticoduodenectomy (P < 0.05), despite a similar degree of surgical trauma defined by the operation length and volume of blood loss during surgery. Peak IL-6 concentration observed in a patient who underwent esophagectomy was about 100-fold greater in fluid drained from the thorax than in the peripheral blood. IL-6 mRNA was demonstrated in leukocytes from thoracic and abdominal exudate at 6, 24 and 48 h after surgery. In contrast, IL-6 mRNA could not be detected in leukocytes from the peripheral blood. Similar findings were also observed for interleukin 8 (IL-8). However, interleukin 1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha) were detected only once after surgery in the drainage fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of methylprednisolone on the cytokine response in patients undergoing lung surgery

Tumour necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and IL-6, when released in excess, have been suggested to be important host mediators of the immunoinflammatory response to injury and infections. Corticosteroids suppress this response in vitro. This study was undertaken to investigate if a single dose of methylprednisolone (MP) could modify the cytokine response in patients undergoing lung surgery. Twenty-one patients with lung cancer were allocated randomly to treatment with MP 30 mg/kg i.v. (MP group) or isotonic saline (control group). Patients were anaesthetized with a balanced anaesthesia combined with thoracic epidural anaesthesia. MP or saline was administered immediately before induction of anaesthesia. The cytokines in plasma were measured by ELISA, and blood samples were collected preoperatively, at the end of surgery, 4 h later, and 1 and 5 days postoperatively. All patients had detectable IL-6 in plasma. Compared to preoperative values, plasma IL-6 levels in the MP group increased from 114 pg/ml (12-350 pg/ml) (mean, range) to peak value 146 pg/ml (15-580 pg/ml) on the first postoperative day. In the control group, IL-6 levels increased from 99 pg/ml (17-350 pg/ml) preoperatively to 125 pg/ml (10-300 pg/ml) on the first postoperative day. The increases were not significant. TNF alpha was detectable in only two patients, one from each group. Low levels of IL-1 alpha were demonstrated in three patients in the MP group and in four patients in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of anaesthesia and surgery on the immune response

Alterations have been found to occur in every component of immune response during anaesthesia and surgery. These alterations represent the body's general physiological responses and are mainly dependent on the extent of surgery, as well as other factors such as the patient's age and health status, medication and blood transfusion. Anaesthetic and operative complications have profound effects on these responses. Basically, the immune response to anaesthesia and surgery is a beneficial reaction, needed in local host defences and wound healing and in preventing the body from making autoantibodies against its own tissues. The responses may, however, contribute to the development of postoperative infections and spread of malignant disease. During uncomplicated conventional surgery, the immune response usually passes clinically unnoticed without any harmful effects. Absent responses and excessively high responses, on the other hand, harm the patient. Our understanding of immunological phenomena and our possibilities of controlling mediator activation are now lagging behind the technical advances made in operative treatment. If we want to decrease operative morbidity and mortality to below their present levels, more attention should be directed to immune responses to major surgery, injuries and operative complications with massive mediator release which place the surgical patient at risk. Experimental evidence suggests that results of treatment in injured and operated patients can in the future be improved by controlling immune responses and their mediator systems. Our current level of knowledge of immune responses is already helping us to avoid many immune-mediated complications. However, routine interference with these responses is not indicated.

Radiation and surgical stress induce a significant impairment in cellular immunity in patients with esophageal cancer

The effects of preoperative radiation plus surgical stress on immunity were examined in 29 patients with esophageal cancer, including 14 patients who experienced radiation therapy and 15 who did not, as well as 15 age-, sex- and body weight-matched control subjects. Absolute numbers of the total lymphocytes and OKT3 (all T cells), OKT4 (helper/inducer T cells) and OKT8 (suppressor/cytotoxic T cells) positive lymphocytes were almost the same in both patient groups before treatment. Both the in vitro response to phytohemagglutinin (PHA) and antibody dependent cell-mediated cytotoxicity (ADCC) were depressed in the patients when compared to the controls before treatment. Dual treatment of radiation and surgery led to a marked reduction of lymphocytes in the numbers and activities of PHA and ADCC, when compared to findings in the non-radiation group. Especially, the number of OKT4 positive lymphocytes and the OKT4 to OKT8 ratio decreased most and recovery was slow. While ADCC activity in the non-radiation group recovered at 28 postoperative days (POD), the response to PHA did not return to the pretreatment levels. Serum levels of IgG, IgM and IgA were within normal limits throughout the course of treatment. The B1 (all B cells) positive lymphocytes significantly decreased after the treatments. These results suggest that radiation plus surgery shifts the host immunity toward immunosuppression and induces a significant impairment of cellular immunity in patients with esophageal cancer.

Ranitidine for prevention of postoperative suppression of delayed hypersensitivity

Cell-mediated immunity was assessed by skin testing with seven delayed-type common antigens in 20 patients undergoing major abdominal surgery and in 20 nonoperative control subjects. The 20 surgical patients were randomized to perioperative ranitidine (50 mg every 6 hours for 72 hours) or no ranitidine. The 20 control subjects received either no ranitidine or ranitidine in the same dosage as the surgical patients. Skin tests were performed 2 days before and 1 day after operation with the same time schedule in the control subjects. Postoperatively, the diameter of the positive skin test area decreased in each of 10 patients without ranitidine (p less than 0.006) but increased in 9 and was unchanged in 1 of the ranitidine-treated patients (p less than 0.01). The skin test changes were similar during the two tests in ranitidine-treated surgical patients and the nonoperative control subjects. Ranitidine did not amplify the response in the nonoperated group. The potential role of histamine blockade in reversal of other aspects of postoperative immunosuppression and reduction in the risk of infection should be explored.

Selective, histamine-mediated immunosuppression in laryngeal cancer

Immunosuppression observed even in the earliest laryngeal cancers can be, in part, reversed with H2 histamine antagonists. In an effort to explain this, we tested whether histamine could evoke changes in endogenous antitumor lymphokine production using tonsil lymphocytes as test cells. We have observed that lymphocytes, treated in vitro with histamine, display a significant suppression of lymphokine production and mixed lymphocyte proliferation response following galactose oxidase treatment. Interferon gamma production was reduced to less than 2% of control value in the presence of histamine. In contrast, the lymphokine-activated killer cell activity induced by purified, natural interleukin-2 was not affected by similar concentrations of histamine. Histamine appears to exert its inhibitory effect by stimulating the production of a substance released by suppressor T cells. The suppressive effects observed could be reversed by concomitant or sequential treatment with cimetidine or ranitidine and not by H1 histamine antagonists, indicating that it occurs through an H2 histamine receptor. These experiments suggest that histamine may have a profound suppressive effect on the lymphocyte population studied.