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Impact of minimally invasive trans-cervical thymectomy on outcome in patients with myasthenia gravis.

OBJECTIVE: To study the impact of minimally invasive trans-cervical thymectomy on the incidence of remission of patients with myasthenia gravis (MG) in a single institution over a 10-year period. METHODS: A total of 120 consecutive patients referred for video-assisted trans-cervical thymectomy between 1991 and 2000 were included in the analysis. Complete remission was defined as no symptoms and no treatment for 6 months, and remission as minimal ocular symptoms (slight ptosis) or treatment with pyridostigmine only for 6 months. RESULTS: There were 86 females and 34 males with a median age of 33 (range 14-79) and 36 years (range 12-68), respectively. Symptoms of MG lasted between 2 months and 17 years before thymectomy (median 10 months). Surgery was converted to a partial upper sternotomy in 23 cases (19%). The median hospital stay decreased from 2 days (range 1-8) before 1994 to 1 day (range 1-8) thereafter (p<0.0001). Postoperative complications occurred in four patients (3.3%). After a median follow-up of 48 months (range 6-117 months), 50% of the patients were in complete remission (41%) or in remission (9%). Kaplan-Meier estimates rate of complete remission were 30% after 5 years of follow-up and 91% after 10 years. CONCLUSIONS: Minimally invasive trans-cervical thymectomy can be performed with short hospital stay and low morbidity, and achieve excellent durable results at 10 years.

Adult↗

Safety for preoperative use of steroids for transsternal thymectomy in myasthenia gravis.

OBJECTIVE: Effects of preoperative steroids on morbidity and mortality after transsternal thymectomy are analyzed. METHODS: There were 620 transsternal thymectomies for myasthenia gravis performed in the period 1973-2002. There were 547 patients with nonthymomatous myasthenia, including 17 patients submitted to repeated thymectomy (rethymectomy) and 46 patients with thymoma. There were 522 upper median sternotomies performed in the period 1973-1997 and 98 complete median sternotomies performed in the period 1998-2002 (74 patients without thymoma, 7 thymomas and 17 rethymectomies). One hundred and seventeen of these 620 patients were taking steroids preoperatively. The impact of steroids use on postoperative respiratory insufficiency (ventilator), need for tracheostomy, superficial wound dehiscence, superficial wound suppuration, sternal dehiscence and mortality was analyzed. RESULTS: The rate of morbidity and mortality in the steroids and the no-steroids groups included respiratory insufficiency necessitating the use of a ventilator in 46/503 patients from the no-steroids group (9.1%) and 8/117 patients from the steroids group (6.8%; P = 0.4260), need for tracheostomy in 14/503 patients from the no-steroids group (2.8%) and 3/117 patients from the steroids group (2.6%; P = 9054). Complications with wound healing (including sternal dehiscence, superficial wound dehiscence and superficial wound suppuration) occurred in 47/503 (9.3%) patients from the no-steroids group and in 1/117 (0.9%) patient from the steroids group (P = 0.0023) The overall complications rate was 30.6% (154/503) in the no-steroids group and 11.1% (13/117) in the steroids group (P = 0.0001). Mortality rate in the no-steroids group was 0.4% (2/503 patients) and none in the steroids group. Morbidity in patients with complete sternotomy was low, respiratory insufficiency in three patients (3.1%), and superficial wound suppuration in one patient (1.0%), no other morbidity and no mortality. Changing morbidity in periods 1973-1980, 1981-1990 and 1991-2002 is analyzed. CONCLUSIONS: Preoperative use of steroids for transsternal thymectomy in patients with myasthenia gravis had no negative impact on morbidity and mortality, conversely, the results in patients taking steroids were better, with significant difference of results regarding the overall complication rates and the overall complication rates of wound healing.

Adult↗

Long-term follow-up after thymectomy for myasthenia gravis: thoracoscopic vs open.

PURPOSE: The aim of this study was to determine if patients are in remission or weaning off medication after thymectomy for myasthenia gravis (MG) and to examine the thoracoscopic versus open approaches. METHODS: A retrospective review of all patients who underwent thymectomy for MG at a tertiary referral center between 1992 and 2004 (N = 14). Six patients (42.9%) underwent thoracoscopic resection. Eight patients underwent open resection; 5 (35.7%) had median sternotomy and 3 (21.4%) by transcervical approaches. Follow-up was obtained in 12 (85.7%) of 14 patients by both chart review and telephone. The mean follow-up was 43.0 months (range, 4-111 months). Statistical significance was determined by Student's t test or Fisher's Exact Test. RESULTS: The thoracoscopic group had a mean operating time of 138.8 minutes compared with 139.8 minutes in the open group (P = .9). The thoracoscopic group had a mean estimated blood loss of 7.5 mL compared with 52.5 mL in the open group (P = .02). The mean length of stay for the thoracoscopic group was 1.5 days (range, 1-2 days) and was 10.6 days (range, 3-41 days) in the open group (P = .13). Three (60%) of 5 patients were entirely off medication in the thoracoscopic group at the time of follow-up compared with 3 (50%) of 6 patients in the open group (P = 1.0). In the thoracoscopic group, 5 (83.3%) of 6 were in class 1 to 3 of the DeFilippi classification (complete remission or improved with decreased medication requirements). One patient had no change in symptoms (class 4). In the open group, 5 (83.3%) of 6 were classified as DeFilippi 1 to 3 at the time of follow-up, and one patient had worsening symptoms (class 5). CONCLUSIONS: Both thoracoscopic and open approaches to thymectomy in patients with MG are effective, with more than 80% of patients in both groups in remission or with improvement at the time of follow-up. The thoracoscopic group has the added benefits of decreased estimated blood loss, decreased length of hospital stay, and improved cosmesis. We advocate the thoracoscopic approach for thymectomy in the treatment of juvenile MG.

Adolescent↗

Expanded indications for transcervical thymectomy in the management of anterior mediastinal masses.

BACKGROUND: Transcervical thymectomy (TCT) is an accepted though controversial approach for thymectomy in myasthenia gravis (MG). The suggestion of thymoma on computed tomography (CT) has been considered a contraindication to TCT. We sought to determine whether the indications for TCT could be safely expanded to include selected patients with thymomas as well as other types of anterior mediastinal masses. METHODS: Between January 1992 and September 1999, we performed 121 TCTs: 98 in patients with MG and 23 in patients without MG. The patients' records were retrospectively reviewed. RESULTS: Among the 98 MG patients, 28 had CT scans suspicious for thymoma. Of these, 14 had a thymoma pathologically. These were classified as stage I (5), stage II (8), and stage III (1). Five patients required extension of the incision for completion of the procedure. There have been no thymoma recurrences to date with a mean follow-up of 48 months (range 3 to 96 months). In the 23 patients without MG, 12 had new anterior mediastinal masses, 4 had a history of treated lymphoma, 1 had a history of treated germ cell tumor, and 6 had suspected mediastinal parathyroid adenoma. Diagnostic tissue was obtained in all patients undergoing the procedure for diagnosis, and in 4 of 6 patients, a parathyroid adenoma was successfully resected. CONCLUSIONS: Transcervical exploration and thymectomy offers a less invasive approach to the diagnosis and/or definitive treatment of selected anterior mediastinal masses. We suggest that it is appropriate to expand its use to several clinical scenarios beyond the typical indication of thymectomy in MG patients without thymoma.

Adenoma↗

Predictors of outcome in thymectomy for myasthenia gravis.

BACKGROUND: Factors determining predictability of response to thymectomy for myasthenia gravis (MG) vary in the literature. METHODS: A 25-year retrospective review (1974 to 1999) of all thymectomies performed at a single institution was undertaken. RESULTS: In 113 consecutive thymectomies for MG, women comprised 79% (89 of 113 patients), and mean age was 40+/-15 years. Complications occurred in 14% of patients (16 of 113). In-hospital mortality was 0, but 90-day hospital mortality was 0.88% (1 of 113 patients). Follow-up was obtained in 81% (92 of 113 patients) at a mean of 51+/-59 months postoperatively. Complete remission was achieved in 21% of patients (19 of 92), and marked improvement of MG in 54% (50 of 92), for a total benefit rate of 75%. Fourteen percent (13 of 92) were unchanged, and 11% (10 of 92) were worse. Using univariate analysis, sex, age, and pathology correlated significantly with outcome (p < 0.05): 80% of women (57 of 70) benefited from the procedure, versus 57% of men (12 of 21). Eighty percent (57 of 70) of patients less than 51 years of age were improved or in remission, versus 57% (12 of 22) older than 50. Twenty-three percent (5 of 22) of patients with thymoma deteriorated, versus 7.1% (5 of 70) without thymoma. Sex did not significantly correlate in the multivariate model. CONCLUSIONS: Sex, age, and thymic pathology are potential predictors of outcome in thymectomy for MG, and may shape treatment decisions and target higher-risk patients.

Adult↗

An improved technique to facilitate transcervical thymectomy for myasthenia gravis.

We have used the transcervical method of thymectomy in patients with myasthenia gravis and believe that complete thymectomy is accomplished with minimum morbidity. For the past eight years we have used an improved technique for the transcervical approach, employing a specially designed sternal retractor that permits improved visualization of the anterior mediastinum. We have reviewed 65 patients operated on between 1977 and 1986. Patients were assessed using a modified Osserman classification (0 = asymptomatic; 1 = ocular signs and symptoms; 2 = mild generalized weakness; 3 = moderate generalized weakness; 4 = severe generalized weakness, respiratory dysfunction, or both). The mean grade for all patients at the time of thymectomy was 2.7. At most recent follow-up, the mean clinical grade was 0.5. In addition, 85% of patients were free of generalized weakness, 95% had improved by at least one grade, and 86% had improved by two or more grades. Comparing these results with those reported following thymectomy through a sternotomy reveals that the transcervical approach gives equivalent results.

Adolescent↗

Contemporary management of myasthenia gravis: the clinical role of thymectomy.

Thirty-six patients with myasthenia gravis have been evaluated and treated over the past five years. Eleven patients had ocular myasthenia gravis and responded well to anticholinesterase medications. Twenty-five patients had generalized myasthenia gravis, and 22 of them were initially treated with anticholinesterase medications; 18(82%) failed to improve or to maintain an initial improvement on medication, and 14 of these 18 patients underwent thymectomy. In addition, 3 patients underwent thymectomy as part of their initial treatment during the later part of this study. All thymectomies were performed through a median sternotomy. All 17 patients manifested sustained improvement as judged by a gain in strength and decrease in medications. Thymectomy is beneficial in the treatment of myasthenia gravis, and it is most efficacious when performed early in the course of the disease.

Adolescent↗

Extended thymectomy for myasthenia gravis patients: a 20-year review.

BACKGROUND: Since 1973 we have performed extended thymectomy for myasthenia gravis because of the presence of thymic tissue in the anterior mediastinal fatty tissue. Follow-up results were reviewed and influencing factors were investigated. METHODS: Three hundred seventy-five patients with myasthenia gravis (286 nonthymomatous and 89 thymomatous) who have undergone extended thymectomies were reviewed. The status of the patients was evaluated as follows: A (remission), B (improvement), C (no change), D (deterioration), E (death due to myasthenia gravis). Evaluation was performed at 3 and 6 months, and at 1, 3, 5, 10, 15, and 20 years. The effectiveness of the operation was estimated by the remission rate (RR = A/Total number of patients evaluated) and the palliation rate (PR = A + B/Total number of patients evaluated) at each point. RESULTS: Remission rates of the nonthymomatous patients were 15.2% (3 months), 15.9% (6 months), 22.4% (1 year), 36.9% (3 years), 45.8% (5 years), 55.7% (10 years), 67.2% (15 years), and 50.0% (20 years). Remission rates in the thymomatous patients were 13.6% (3 months), 17.5% (6 months), 27.5% (1 year), 32.4% (3 years), 23.0% (5 years), 30.0% (10 years), 31.8% (15 years), and 37.5% (20 years). Absence of thymoma, younger age, and short duration of the disease were favorable prognostic factors. Thymectomy was effective also in patients with ocular myasthenia gravis. Preoperative steroid administration did not improve the outcome. CONCLUSIONS: Extended thymectomy is an excellent operative procedure for myasthenia gravis in both nonthymomatous and thymomatous patients.

Adult↗

Efficacy and safety of extended thymectomy for elderly patients with myasthenia gravis.

BACKGROUND: The number of elderly patients who are diagnosed as myasthenia gravis (MG) is increasing in Japan. Although several factors affecting thymectomy have been well documented, few studies have focused on the efficacy and safety of thymectomy for elderly patients older than 60 years. METHODS: We evaluated 94 patients with MG who underwent extended thymectomy, and divided them into two groups: patients younger than 59 years and patients older than 60 years. Preoperative patient data, pathology of the thymus, complications, and clinical outcome were evaluated. RESULTS: In 69 young patients and 25 elderly patients, we observed no significant differences between the two groups with regard to preoperative data. Thymic hyperplasia was present in 45% of the young group and 16% of the elderly group. Remission and improvement rate were 40% and 57% in the young group and 8% and 75% in the elderly group, respectively. There were no serious complications, except one early death due to gastrointestinal bleeding in the elderly group. CONCLUSIONS: We conclude that thymectomy is a safe and effective alternative for elderly patients with MG.

Adolescent↗

Neonatal thymectomy: does it affect immune function?

OBJECTIVE: The purpose of this study was to determine whether thymectomy in the newborn has a negative effect on immune function. METHODS: Twenty-five neonates (<30 days) who had thymectomy at congenital heart repair were prospectively studied to determine immune function. The percentage of T-cell subtypes including CD3 (all T cells), CD4 (helper T cells), and CD8 (suppressor T cells) was determined. In six patients, further testing of CD4 cells was done to determine whether they were newly formed, recent thymic emigrants (CD4, CD45, and RA+), or older educated lymphocytes (CD4, CD45, and RO+). Response to the mitogen phytohemagglutinin and to tetanus toxoid were determined, as were antibody titers to tetanus. Samples were drawn before the thymectomy, at approximately 3 months after immunization and at 1 year. Ten age-matched control patients were tested. At follow-up, parents were asked about infections. RESULTS: Prethymectomy T-cell subsets were all normal and comparable to controls. At 12 months, the percent of CD3 was significantly less than in the control group (48% +/- 3% versus 64% +/- 2% [mean +/- standard error of the mean]; p < 0.01) as was CD4 (31% +/- 2% versus 46% +/- 2% [mean +/- standard error of the mean]; p = < 0.01). CD8 did not drop. Surprisingly, the percent of CD4 that were recent thymic emigrants did not decrease significantly (50% +/- 8% versus 60% +/- 6% [mean +/- standard error of the mean]; p = not significant). Lymphocyte blastogenesis to phytohemagglutinin and tetanus toxoid and antibody to tetanus were all normal at 12 months. No patient required readmission for infection, and there were the expected number of minor infectious events (median 3; 95% confidence interval 1,4). CONCLUSION: Thymectomy in neonates results in a modest but significant decrease in T-lymphocyte levels, but there is no compromise in immune function.

Antigens, CD↗

The effect of thymectomy on autoreactive T- and B-lymphocytes in myasthenia gravis.

Eleven patients with myasthenia gravis were followed for three years after thymectomy. Acetylcholine receptor-specific T-cell stimulation was found in 8/11 patients before operation as compared to 2/11 three years after thymectomy. Changes of T-cell antireceptor-reactivity were commonly paralleled by changes in disease severity. The numbers of cells secreting IL-2 upon stimulation with human acetylcholine receptor correlated with those secreting IFN-gamma. T-cell reactivity against a monoclonal acetylcholine receptor antibody did not decrease after thymectomy. Such reactivity could reflect a beneficial immune response counteracting anti-receptor reactivity. The frequency of autoantibody-secreting cells remained unchanged, while the serum concentration of acetylcholine receptor antibodies started to decrease one year after thymectomy. All examined thymus-cell suspensions contained autoreactive T- and B-lymphocytes. There was a preferential enrichment of autoreactive lymphocytes in the thymus in a few patients with recent onset of disease.

Adult↗

[Prognostic factors and outcome of thymectomy in 80 cases of myasthenia gravis].

OBJECTIVES: To analyze the results of thymectomy in our series of patients with myasthenia gravis (MG) and to study the influence of the most common prognostic factors. MATERIAL AND METHODS: Eighty MG patients over a period of 23 years underwent thymectomy consecutively in our hospital. Preoperative assessment included clinical evaluation of muscle weakness, edrophonium testing, electromyography, lung function testing, chest X-rays and CAT scans. Symptoms were assessed by the Osserman scale. The surgical approach was amplified transsternal thymectomy. The prognostic factors studied were sex, age, clinical stage, duration of disease before surgery and histology of the thymus. Clinical outcome was assessed using Millichap and Dodge's criteria. Follow-up was by the chest surgery and neurology departments. RESULTS: Complete remission was observed in 29 cases (36.2%) and significant improvement in 42 (52.5%). Complications developed in 9 patients (11.2%). Most patients were women (53/27) and outcomes for men and women were not statistically different. Mean age was 36 years (range 11-79), with no significant difference in outcome for patients who were older or younger than 60 years of age. Nor were differences evident related to presurgical clinical stage or levels of severity (I + IIa/IIb + III). Differences in outcome were highly significantly related to duration of disease (< 24 / > 24 months) (p = 0.0022), such that outcome was more satisfactory when the pre-surgical course of disease was shorter, provided that no thymoma was present. CONCLUSIONS: Amplified transsternal thymectomy was safe and effective for those patients with MG. When disease had been present for less than two years, the prognosis was better.

Adolescent↗

[The treatment of myasthenia gravis by video thoracoscopic thymectomy. The technic and the initial results].

The primary role of thymectomy for the treatment of myasthenia gravis is currently undisputed. Traditionally, the approach of choice has been sternotomy, although a transcervical route has also been advocated because of its lower rate of associated morbidity. Our department performed thymectomy using a video-assisted thoracoscopic technique in 7 patients (2 men and 5 women) between March 1993 and October 1995. The patients' mean age was 43.4 years (range 20 to 66 years). Complications were few, consisting of 2 cases of pneumothorax due to contralateral opening of the pleura, resolved by pleural drainage. No deaths occurred. Clinical results over periods of observation ranging from 14 to 44 months were excellent in 2 cases of complete remission; good in 3 patients with considerable reduction in drug requirements; and fair in 2 patients who continued to need the same doses of medication throughout the 14 months after thymectomy. The technique we propose is less aggressive than mid-sternotomy, offering incontrovertible advantages and leading to faster. No patient required assisted ventilation for longer than 4 hours and the maximum time spent in the intensive care unit was 24 hours. We therefore suggest that thymectomy to treat myasthenia gravis be performed by thoracoscopy.

Adult↗

Extended thymectomy in myasthenia gravis: a team-work of neurologist, thoracic surgeon and anaesthesist may improve the outcome.

OBJECTIVE: We reviewed our overall experience on 163 patients, affected by myasthenia gravis, who underwent thymectomy between 1976 and 1998. A comparison between the oldest series of 72 patients (January 1976-December 1992), referred by various neurologists and operated on through different approaches, and the last 91 patients (January 1993-December 1998), taking part in a strict diagnostic-therapeutical programme, was made. METHODS: Anagraphic data, duration of symptoms, the surgical approach, necessity of respiratory assistance, the hospital stay, histopathological findings, preoperative and postoperative Osserman classification, as well as medications, were globally analyzed and then compared in the two groups. RESULTS: Significant differences in the length of hospitalization (8.7 days vs. 4.2 days; P=0.00001) and in the prolonged intubation rate (18 vs. 0; P<0.000001) were observed in the most recent series. Patients in the pre-operative Osserman stage I and operated on in the second period had a higher complete remission rate at the univariate analysis (P<0.001 and P<0.0001, respectively). At the multivariate analysis the only parameter which affected the outcome was to be operated on in the second period (P<0.01). CONCLUSIONS: Our experience confirms the role of the extended thymectomy in the treatment of myasthenia gravis. Whenever an extended thymectomy was performed through a complete sternotomy it was a quick procedure, with short hospitalization and acceptable cosmetic results. A careful pharmacological control of the myasthenic symptoms and the presence of team-work among neurologist, thoracic surgeon and anaesthesist in the peri-operative setting reduce the incidence of complications and might increase the efficacy of the thymectomy.

Adolescent↗

Observations on the effect of thymectomy on chemical carcinogenesis in the hamster cheek pouch.

The effects of thymectomy and sham operation on 9,10-dimethyl-1,2-benzanthracene (DMBA) induced tumours of the hamster cheek pouch were studied in Syrian golden hamsters. The incidence of carcinomata and papillomata with intra-epithelial carcinoma (atypical papillomata) in these animals was compared with that in control animals treated with DMBA alone, without surgical intervention.In 32 non-operated control animals, the average tumour yield after 12 weeks' DMBA application was 2·13 carcinomata and 1·22 atypical papillomata per treated pouch. In 14 animals thymectomized at the age of 2 weeks, the tumour yield was 0·21 and 0·36, respectively, and in 10 animals thymectomized when adult, it was 0 and 0·1 respectively. In 9 animals sham operated on at the age of 2 weeks, an average of 1·56 carcinomata and 1·22 atypical papillomata were found, but in 13 animals which were sham operated when adult, the tumour yield was 0·54 and 0·15 per treated pouch, respectively.The results suggest that the time of thymectomy in relation to DMBA treatment may be of importance and that thymectomy, when performed in 2-week old hamsters, inhibits DMBA tumourigenesis. The major effect of thymectomy performed in adult hamsters appears to be related to stress following surgery.

Age Factors↗

[The thoracoscopic thymectomy for myasthenia gravis].

UNLABELLED: Myasthenia gravis (MG) is a chronic autoimmune disease that usually responds positively to treatment with thymectomy. Standard surgical procedures have been shown to result in a favorite outcome. The optimal surgical access, however, is under discussion. PATIENTS AND METHOD: In a prospective study conducted between 8/97 and 4/05, 173 patients with MG underwent thoracoscopic thymectomy, for which a left-sided approach was generally applied. An analysis of the intraoperative and postoperative course was performed in 137 patients (8/97 and 12/03), as well as of the impact of the surgical procedure on further development of the disease. The results obtained were compared with those published in the literature, with particular reference to results obtained with open surgery. In 8 patients, the procedure was converted to an anterolateral thoracotomy or sternotomy, so we examined 129 patients, which were operated thoracoscopically. RESULTS: The patients in this study were 93 females and 36 males, with a mean age of 35.8 (range: 9-83) years. The mean preoperative duration of the disease was 22.9 (range: 1-140) months. The duration of operation was 50 to 85 minutes, the blood loss was lower than 100 ml. The mean follow up was 24.7 (range: 1-57) months. Complete remission was noted in 30 patients (23.3 %), and improvements reflected either in a reduction of the required medication, or a decrease in symptom severity, were seen in a total of 86 patients (66.6 %). CONCLUSION: Complete thoracoscopic thymectomy is a technically feasible operation, and as effective as conventional open surgery. Remissions or symptomatic improvements were observed in more than 89 % of the patients. The low morbidity rate, in combination with excellent cosmetic results, has led to increasing acceptance of the operation both by patients and neurologists. Therefore, thoracoscopic thymectomy represents a new, alternative method for treatment of patients with MG.

Adolescent↗

Long-term evaluation of extended thymectomy with anterior mediastinal dissection for myasthenia gravis.

BACKGROUND: Thymectomy for the treatment of myasthenia gravis (MG) is well established. The extent of resection, however, remains a source for debate. Outcomes for newer surgical techniques need to be compared to more extensive procedures. METHODS: A retrospective review was done of 64 consecutive patients who underwent transsternal thymectomy with extended anterior mediastinal dissection for MG between 1979 and 2000 and who were operated on by a single surgeon. RESULTS: Fifty-six patient charts were available, providing 58 operative procedures. Three patients had died of unrelated causes. The mean age of symptom onset was 36.0 +/- 2.5 years, with a mean duration of 3.3 +/- 0.5 years until surgery was undertaken. The mean length of follow-up was 6.8 +/- 0.8 years. Operative procedures were associated with a 10.3% major morbidity rate and no mortality. Drug-free remission was achieved in 50.0% of the patients, and symptoms were absent or improved in 76.8% of the patients. Patients followed up long-term (>10 years) achieved the greatest remission rate (71.4%) and symptomatic improvement (85.7%). After thymectomy, the mean dosages of prednisone and Mestinon decreased by 69.3% and 58.8%, respectively. CONCLUSIONS: Extended thymectomy provides excellent overall symptom improvement, which is enhanced over time. This review provides a basis for long-term comparison with other less invasive and perhaps less extensive procedures.

Adolescent↗

Genetic control of the immune response. The effect of thymectomy on the primary and secondary antibody response of mice to poly-L(tyr, glu)-poly-D, L-ala--poly-L-lys.

The effect of thymectomy on the genetically controlled murine immune response-1 (Ir-1) to the synthetic polypeptide poly-L(Tyr, Glu)-poly-D, L-Ala--poly-L-Lys [(T, G)-A--L] was studied with both aqueous and adjuvant immunization regimens. Adult thymectomy (combined with irradiation and bone marrow transfusion) did not affect the aqueous antigen-induced (IgM) primary response of either high or low responder mice, but did ablate the (IgG) secondary or tertiary response, a response which is restricted to the high responder strains. Adult thymectomy also blocked the normal high response to (T,G)-A--L in Freund's adjuvant in high responder mice and the high response to methylated bovine serum albumin (MBSA)-(T,G)-A--L in low responder mice. Neonatal thymectomy was also effective in blocking the response to (T, G)-A--L in Freund's adjuvant in high responder mice. These data are consistent with the concept that the Ir-1 gene effect is mediated via thymus cell interaction with antigen and with "B"-cells during the time of induction of IgG antibody formation.

Adjuvants, Immunologic↗