Lymphocyte phenotypes in bronchoalveolar lavage and lung tissue in sarcoidosis and idiopathic pulmonary fibrosis

To determine whether the lymphocytes recovered by bronchoalveolar lavage (BAL) are representative of the cells found in lung tissue, we identified and enumerated lymphocyte phenotypes directly in lung tissue and lavage fluid with monoclonal antibodies (Leu 4-total T, Leu 3-helper T, Leu 2-suppressor/cytotoxic T cells) and an avidin-biotin peroxidase method in 6 patients with sarcoidosis and 6 patients with idiopathic pulmonary fibrosis (IPF). We found that the absolute numbers of each phenotype and the ratios of Leu 3/Leu 4, Leu 2/Leu 4, and Leu 3/Leu 2 in lavage fluid and tissue correlated well for both groups of patients. This supports the notion that the lymphocytes recovered by BAL are representative of the cells present in the lung. However, when cell recovery was expressed as the number per milliliter of recovered lavage fluid, there were no significant correlations between lavage fluid and tissue for any phenotype in the IPF group. The degree of restrictive impairment was significantly greater and the lavage fluid recovery was significantly lower in this group than in the sarcoid group. Thus, the lymphocytes recovered by BAL appear to mirror the types of cells found in lung tissue in these 2 forms of diffuse interstitial disease, but this relationship may not hold when there is a severe restrictive impairment and a low recovery of lavage fluid.     

Bronchoalveolar lavage in primary pulmonary lymphoma with monoclonal gammopathy

We performed bronchoalveolar lavage in a patient with pulmonary lymphoma and IgM lambda monoclonal serum gammopathy previously not diagnosed accurately by histologic examination and not treated for 5 yr after detection of a pulmonary infiltrate. The infiltrate increased slowly in size accompanied by coughing and sputum and a gradual increase in serum IgM throughout the 5-yr period. High IgM in the lavage fluid was noted with an IgM/albumin ratio 4.8 times higher in the lavage fluid than in the serum. Protein immunoelectrophoresis of the lavage fluid was identical to that of the serum. A primary pulmonary lymphoma was diagnosed on the basis of findings in the lavage fluid. The patient showed decreased serum IgM and marked improvement of the infiltrate by chemotherapy and radiation. Thus, bronchoalveolar lavage, including analysis of the proteins in lavage fluids, appears to be a simple and useful method for diagnosing primary pulmonary lymphomas.     

Immunoglobulin G antineutrophil cytoplasmic antibodies are produced in the respiratory tract of patients with Wegener's granulomatosis

Wegener's granulomatosis (WG) is a small-vessel vasculitis of unknown etiology that usually involves the upper and lower respiratory tract and the kidneys. Recently, an association has been made between the presence of serum antineutrophil cytoplasmic antibodies (ANCA) and WG. Because WG frequently involves the lung, we sought to evaluate bronchoalveolar lavage (BAL) fluids obtained from 14 patients with WG for the presence of ANCA. Immunoglobulin (Ig) G ANCA was found in the BAL with the same staining patterns as observed in the serum. Patients with active disease had the highest serum and BAL IgG ANCA titers. IgA or IgM ANCA was not detected in the serum or BAL of these patients. Protein analysis of BAL fluid revealed that patients with active, untreated WG had approximately a fourfold elevation in total protein (41.3 versus 10.5 mg/dl), with a disproportionately greater increase in the ratio of IgG to albumin (BAL IgG index = 1.49, normal = 0.74; p = 0.027). The increase of the IgG index in patients with active WG suggests that local production of IgG ANCA occurs in the lungs.     

Reliability of cell counts and protein determinations in serial bronchoalveolar lavage procedures performed on healthy volunteers

We measured the variability in volume, total cells, cell types, and proteins in the bronchoalveolar lavage fluid recovered from 10 volunteers (five smokers, five non-smokers) lavaged repeatedly over a three-year period. Thirty lavages were performed using a rigorously standardized approach. Differential counts on the cytospin preparations were performed by three independent readers and interobserver variability in the interpretation of these counts measured. Variability in interpreting the cellular counts was less in smokers than non-smokers and decreased as the number of cells of any particular type increased. Only one reader interpreting the mean percentage of cells recovered of one cell type (neutrophils) in only one smoking group, the nonsmokers, was significantly different from the other two. There was also considerable variability in bronchoalveolar lavage fluid total protein, albumin, IgG, and IgA. Expressing albumin and IgG as a percentage of total protein recovered and expressing IgA and albumin as a ratio in nonsmokers lessened the variability of these parameters. Mean and standard deviations of the cellular and protein concentrations showed that large differences in these parameters would be necessary in order to attribute these changes to changes in the underlying pulmonary status. Excessive variability in nearly all parameters in this group without recognized lung disease challenges the usefulness of this test in the clinical assessment of patients serially followed because of underlying lung disease.     

Detection of HTLV-III/LAV-specific IgG and antigen in bronchoalveolar lavage fluid from two patients with lymphocytic interstitial pneumonitis associated with AIDS-related complex

Lymphocytic interstitial pneumonitis, a disorder of unknown cause, has been described in association with infection by the retrovirus human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). This report describes the isolation of HTLV-III/LAV in bronchoalveolar lavage fluid and the quantitation of antibodies directed against HTLV-III/LAV in bronchoalveolar lavage fluid and peripheral blood of two patients with lymphocytic interstitial pneumonitis associated with acquired immune deficiency syndrome-related complex. The ratio of the concentrations of HTLV-III/LAV-specific IgG to total IgG in the bronchoalveolar lavage fluid of both patients was higher than that of the peripheral blood. These findings are consistent with the hypothesis that lymphocytic interstitial pneumonitis is sometimes associated with HTLV-III/LAV infection of pulmonary tissue that evokes a specific humoral immune response locally in the lung.     

Pulmonary involvement in patients with HTLV-I-associated myelopathy: increased soluble IL-2 receptors in bronchoalveolar lavage fluid

A chronic spastic myelopathy associated with HTLV-I infection (HTLV-I-associated myelopathy: HAM) shows subclinical pulmonary involvement with bronchoalveolar T lymphocytosis. In the present study, we investigated 18 patients with HAM: five HTLV-I carriers without myelopathy and 13 normal control subjects seronegative for HTLV-I to determine if soluble IL-2 receptors (IL-2R), a marker of lymphocyte activation, were increased in serum and bronchoalveolar lavage (BAL) fluid from HAM patients. Serum IL-2R levels were significantly increased in patients with HAM as compared to normal control subjects (HAM versus control subjects: 633 +/- 395 versus 278 +/- 53 U/ml, p less than 0.01). There was also an increase of serum IL-2R levels in one of five HTLV-I carriers. BAL levels of soluble IL-2R were low but detectable in four normal control subjects and in one HTLV-I carrier. In HAM patients, however, soluble IL-2R levels in BAL fluid were remarkably elevated (173 +/- 110 U/mg of albumin) and were nearly 13 times higher on average than in serum (BAL fluid/serum ratio: 13 +/- 10). In patients with HAM, lavage IL-2R levels correlated well with the number of T lymphocytes (CD3+ cells) and CD4+ cells in BAL fluid (p less than 0.01). Furthermore, BAL lymphocytes obtained from HAM patients synthesized DNA spontaneously when cultured in vitro. These results suggest that, in HAM, T lymphocytes increased in the lung are activated locally to produce soluble IL-2R. Based on the results of this study, we conclude that immunologic mechanism(s) may play an important role in the development of pulmonary lesions in HAM patients.     

Lymphocyte subpopulations in bronchoalveolar lavage in Sj?gren's syndrome. Evidence for an expansion of cytotoxic/suppressor subset in patients with alveolar neutrophilia

We initiated this study to determine the cellular composition and T-lymphocyte subpopulations of fluid from bronchoalveolar lavage from 15 patients with primary Sj?gren's syndrome (1SS), six patients with secondary Sj?gren's syndrome associated with primary biliary cirrhosis (2SS-PBC), eight patients with secondary Sj?gren's syndrome associated with collagen-vascular diseases (2SS-CVD), and 12 normal subjects. All were nonsmokers who were free of clinical pulmonary symptoms and had normal findings on chest roentgenograms. Lymphocyte subsets were identified by mouse monoclonal antibodies that were specific for T-cells, helper/inducer, and suppressor/cytotoxic (namely, OKT3, OKT4, and OKT8). Patients with 1SS, patients with 2SS-PBC, and patients with 2SS-CVD had a significantly increased percentage of lymphocytes in fluid from bronchoalveolar lavage (respectively, 21.6 +/- 3.7 percent, 24.3 +/- 6.1 percent, and 25.6 +/- 3.9 percent) compared with the normal value of control subjects (9.9 +/- 1.5 percent). In addition, two of the 15 patients with 1SS and five of the eight patients with 2SS-CVD demonstrated an increased percentage of alveolar neutrophils. The predominant T-cell subset in patients with 1SS was T4+, and the mean T4:T8 ratio was normal. The percentage of T4+ cells was increased in patients with 2 SS-PBC, resulting in an increased T4:T8 ratio. In contrast, patients with 2 SS-CVD demonstrated a markedly increased percentage of T8+ cells, reflected by a shift in the T4:T8 ratio which was inverted. Patients with Sj?gren's syndrome and with neutrophilia on bronchoalveolar lavage had a marked expansion of the T8+ lymphocyte subpopulation, where as patients with Sj?gren's syndrome and with pure lymphocytosis on bronchoalveolar lavage showed predominantly T4+ cells. In addition, we found a strong positive correlation between the number of neutrophils and the number of T8+ cells in bronchoalveolar lavage from patients with Sj?gren's syndrome (r = 0.74; p less than 0.05). Until the functional activities of OKT4+ and OKT8+ cells are better defined, the role that these cells play in the pathogenesis of pulmonary disease in Sj?gren's syndrome remains unclear.     

Progression from Crow-Fukase syndrome with double gammopathy (IgM-kappa, IgG-lambda) to primary macroglobulinemia

This report deals with a case of double gammopathy (IgM-kappa, IgG-lambda) with Crow-Fukase syndrome, which developed into primary macroglobulinemia four years after the diagnosis. In May 1980, a 74-year-old woman was admitted to the hospital because of a rapid progression of peripheral neuropathy. The patient was diagnosed as having Crow-Fukase syndrome from the following data: albumin-cytologic dissociation of cerebrospinal fluid, peripheral edema, diffuse hyperpigmentation of the skin, diabetic glucose intolerance, serum double gammopathy (IgM-kappa, IgG-lambda) and hepatomegaly. The administration of prednisolone yielded the improvement of neuropathy. In December 1984, serum IgM level was increased from 104 mg/dl to 3,025 mg/dl. Plasma cells in the bone marrow increased in the percentage from 5.6% to 18.4%, and then Bence Jones protein (kappa type) was excreted in the urine. No antibody activity to myelin antigens was detected in the serum. The patient died of cerebral infarction in 1985. At postmortem examination, lymphomatous involvement was found in the jejunum. At the immunohistological examination of the tumor specimens, the morphology and the distribution of IgM- and IgG-positive cells corresponded to that of kappa- and lambda-positive cells, respectively. A small number of cells containing both kappa and lambda light chains were also demonstrated. It seems likely that IgM (kappa)- and IgG (lambda)-positive cells were derived from the common precursor cells.     

The BALB/c mouse as a model for immunological studies of microfilariae-induced pulmonary eosinophilia

Tropical pulmonary eosinophilia (TPE) is believed to result from extreme immediate hypersensitivity to microfilariae localized in the pulmonary vasculature of some persons with lymphatic filariasis. Female BALB/c mice repeatedly immunized by ip injection of Brugia malayi microfilariae become amicrofilaremic within 24 hr of iv parasite challenge, whereas non-sensitized control animals remain patent for greater than 72 hr. Immunized, but not control mice, develop peripheral blood and pulmonary eosinophilia (2,000 cells/mm3 and 65,000 cells/bronchoalveolar lavage, respectively). Serum and bronchoalveolar lavage filarial-specific IgG antibodies are greater in sensitized mice than in controls (ELISA absorbance values 20- and 10-fold higher, respectively). Serum IgE antibody levels are also greater (P less than 0.01) in immunized parasite-challenged mice than in controls (mean cpm 125I-labeled anti-mouse IgE bound to B. malayi antigen-coated Sepharose beads: 7,852 vs. 1,741, respectively). This model exhibits several of the major features of human TPE: amicrofilaremia, elevated levels of serum IgG and IgE antibodies to microfilariae, and blood and pulmonary eosinophilia. This model may be useful in the examination of the role of filarial antigen-specific lymphoid cells and antibodies in regulating the pathologic responses to microfilariae trapped in the lung.     

Multiple myeloma of IgG-lambda type associated with asymptomatic primary biliary cirrhosis

Multiple myeloma associated primary biliary cirrhosis (PBC) is very rare and only two cases have been reported. In this paper, we reported the first case of male patient with asymptomatic PBC and multiple myeloma. A 66 year-old Japanese male was referred to our hospital for the further examination of a monoclonal gammopathy. He was diagnosed of multiple myeloma (IgG-lambda type) because of 2.3 g/day of Bence Jones proteinuria (lambda type), 3,401 mg/dl of monoclonal IgG (lambda type), 12.8% of bone marrow plasmocytosis and generalized osteoporosis. The alkaline phosphatase was 314 mU/ml and serum IgM level (polyclonal) 937 mg/dl. The patient was started on intermittent courses of melphalan and prednisolone, achieving transient improvement. After two years, hepatosplenomegaly developed gradually and the levels of serum ALP elevated increasingly. At that time, relevant investigation results were: serum ALP 663 mU/ml, serum IgG 4,144 mg/dl, serum IgM 823 mg/dl, positive anti-mitochondrial antibody test x 320. The liver biopsy showed chronic nonsuppurative destructive cholangitis. PBC (stage 1-2 according to Sheuer's criteria) associated with multiple myeloma was diagnosed. A pathogenetic relationship such as loss of immunoregulatory function could be speculated although the simultaneous occurrence of PBC and multiple myeloma could be coincidental.     

Diagnosis of pulmonary strongyloidiasis by bronchoalveolar lavage

Bronchoalveolar lavage was performed on a patient with disseminated strongyloidiasis and 4.5 X 10(7) cells/65 ml of lavage fluid were recovered. Eighty-five percent of cells were polymorphonuclear leukocytes; 15 percent were pulmonary alveolar macrophages. Rhabditiform larvae (1 X 10(4)) were recovered in 65 ml of lavage fluid. This is the first report of bronchoalveolar lavage used in diagnosing disseminated strongyloidiasis.     

A long-survival case of systemic AL amyloidosis with nephrotic syndrome

A 49-year-old Japanese female was initially diagnosed as having monoclonal gammopathy of undetermined significance in June 1993 (IgG lambda: 3,120 mg/dl). Four years later, she developed AL amyloidosis complicated by nephrotic syndrome and renal failure. Before receiving 5 courses of MP therapy (melphalan plus prednisolone), her serum IgG level had decreased in accordance with the appearance of nephrotic syndrome, which led to the leakage of serum immunoglobulin into the urine. After the discontinuation of the MP therapy, hypogammaglobulinemia has been kept over 24 months, though she still shows a leakage of 4-5 g/day of serum protein, including IgG into the urine. There were no signs of the progression of amyloidosis or renal failure, resulting in a good clinical performance status. Hypogammaglobulinemia due to nephrotic syndrome may have prevented the progression of AL amyloidosis in this case.     

Altered immunological reactivity in alveolar macrophages from patients with sarcoidosis

Lung macrophages may play an important role in the pathogenesis of pulmonary sarcoidosis. In this study, the ability of pulmonary macrophages and blood monocytes from sarcoidosis patients, normal controls and disease controls to provide the accessory signal necessary for the concanavalin A-induced activation of normal blood T cells was examined. Blood monocytes from all groups supplied a significantly greater accessory signal than lung macrophages. The accessory capacity of lavage macrophages from sarcoidosis patients varied over a wide range and correlations were sought between these values and other parameters of disease activity. Whilst there was no correlation with clinical parameters, accessory function of alveolar macrophages correlated significantly with the percentage of T helper cells in bronchoalveolar lavage (BAL) fluid (p less than 0.05) and, more closely, with the T helper:T suppressor ratio in BAL fluid (p less than 0.01). This interrelationship between macrophage activity and the T cell infiltrate favours the probability that both cell types participate in the sarcoid disease process and raises the possibility that T cells of both helper and suppressor phenotypes contribute to the pathogenesis.     

Clara cell protein as a marker of Clara cell damage and bronchoalveolar blood barrier permeability.

The 16 kDa Clara cell protein (CC16), an abundant component of airway secretions, has recently been proposed in humans as a pulmonary marker measurable not only in bronchoalveolar lavage fluid (BALF) but also in serum. The aim of the present study was to investigate the changes and determinants of CC16 concentrations in these fluids in normal rats and rats with lung injury. Female Sprague-Dawley rats were given a single i.p. injection of arachis oil (n=20) or chemicals in arachis oil (n=10) that mainly damage Clara cells (4-ipomeanol (IPO) 8 mg x kg(-1) and methylcyclopentadienyl manganese tricarbonyl (MMT) 5 mg x kg(-1)) or endothelial cells (alpha-naphthylthiourea (ANTU) 5 mg x kg(-1)). CC16 concentration (mean+/-sD in microg x L(-1)), measured by a sensitive latex immunoassay, was significantly reduced in BALF of all treated groups (IPO 380+/-100; MMT 730+/-200; ANTU 1,070+/-200; controls 1,700+/-470). The same pattern of decrease was observed in the labelling of Clara cells with an anti-CC16 antiserum as well as in the CC16 messenger ribonucleic acid levels assessed by Northern enzyme-linked immunosorbent assay. In serum, by contrast, CC16 was significantly increased in all treated groups (IPO 31+/-7; MMT 22+/-12; ANTU 52+/-24; controls 15+/-6). This rise of CC16 in serum was associated with an elevation of albumin in BALF which is an index of increased bronchoalveolar/blood barrier permeability. In conclusion, lung injury induces a decrease of the 16 kDa Clara cell protein in bronchoalveolar lavage fluid owing to a reduced production by damaged Clara cells, and an increase in serum protein levels resulting from its enhanced leakage across the bronchoalveolar/blood barrier. This study provides new insights into the understanding of the changes of lung secretory proteins in bronchoalveolar lavage fluid and serum.     

Characteristics of bronchoalveolar lavage fluid in patients with sulfur mustard gas-induced asthma or chronic bronchitis.

PURPOSE: To examine the pattern of immunoglobulins and cellular constituents in bronchoalveolar lavage fluid obtained from patients with sulfur mustard gas-induced asthma or chronic bronchitis as compared with healthy control subjects. SUBJECTS AND METHODS: We studied two groups of nonsmoking veterans with either bronchial asthma (n = 21) or chronic bronchitis (n = 28) believed to have been caused by sulfur mustard gas exposure and a third group of healthy, nonsmoking, non-sulfur mustard gas exposed controls (n = 17). Bronchoalveolar lavage was performed in all three groups. The cellular constituents, albumin content, and immunoglobulin concentrations were determined. RESULTS: The three groups did not differ in age or in the serum albumin and immunoglobulin concentrations. The volume of bronchoalveolar lavage fluid recovered was approximately 10% less in the patients with asthma and chronic bronchitis (P = 0.008). The proportions of lymphocytes among the bronchoalveolar lavage cells were similar in all three groups, whereas the proportion of eosinophils was greater in lavage fluid from the asthmatic subjects than in either the healthy control subjects or the patients with chronic bronchitis (P = 0.0001). Both the total number of the recovered cells per milliliter of lavage fluid and the proportion of neutrophils were significantly greater in bronchoalveolar lavage from patients with chronic bronchitis than in healthy subjects or in the patients with asthma (all P <0.001). CONCLUSION: The bronchoalveolar lavage cellular constituents of patients with sulfur mustard gas-induced asthma and chronic bronchitis are similar to those that have been observed previously in patients with asthma and chronic bronchitis from other common causes.     

Steroid-responsive interstitial pulmonary disease in systemic sclerosis. Monitoring by bronchoalveolar lavage

We describe a 38-year-old woman with systemic sclerosis of recent onset and progressive dyspnea. Studies of pulmonary function revealed a restrictive ventilatory disorder with decreased diffusing capacity. Interstitial fibrosis and infiltration with lymphocytes and plasma cells with formation of follicles were observed in the lung biopsy. Analysis of fluid from bronchoalveolar lavage showed an increase in the total number of cells, with a relative increase in neutrophils. Also, the relative amount of the immunoglobulins, IgG and IgM, was increased. During corticosteroid treatment, rapid improvement of pulmonary volumes occurred, together with disappearance of neutrophils and an increase in the percentage of lymphocytes in the lavage fluid. Later on, the total number of cells in the fluid from bronchoalveolar lavage and the percentage of lymphocytes reached normal values. Bronchoalveolar lavage may be of value in assessing and monitoring pulmonary disease in patients with systemic sclerosis.     

Sauna lung: Hypersensitivity pneumonitis due to Exophiala jeanselmei

A 55‐year‐old man developed progressive cough and dyspnoea after regular attendance at a public steam bath. Hypoxaemia, diffuse pulmonary infiltrates and a predominance of lymphocytes with an increased percentage of CD8+ T cells in his bronchoalveolar lavage fluid suggested hypersensitivity pneumonitis. Microbial cultures from the steam bath room and tank identified Exophiala jeanselmei. Immunoblotting assays from the patient's serum confirmed the major antigenic stimulus. The patient recovered fully after systemic corticosteroid treatment and cessation of further exposure.     

Ascitic fluid bilirubin concentration as a key to choleperitoneum

Total bilirubin concentration was measured in the ascitic fluid and serum of 65 patients with various types of ascites to determine the normal range of these parameters. The mean (+/- SD) ascitic fluid bilirubin was 0.7 +/- 0.8 mg/dl, and the mean ascitic fluid/serum bilirubin ratio was 0.38 +/- 0.44. Subsequently, I recognized choleperitoneum in a patient with bile-stained ascites preoperatively, because the ascitic fluid bilirubin was 18.5 mg/dl and the ratio was 7.1. Laparotomy documented a ruptured gallbladder. An ascitic fluid bilirubin concentration greater than 6 mg/dl with an ascitic fluid/serum bilirubin ratio greater than 1.0 appears to be characteristic of choleperitoneum.     

Smoking-induced changes in epithelial lining fluid volume, cell density and protein.

Bronchoalveolar lavage has proved a useful research technique for recovering cellular and molecular contents of the lower respiratory tract. Because the recovered fluid is variably diluted, an accurate estimation of molecular and cellular concentrations can only be made if the epithelial lining fluid volume recovered is also known. It has been suggested that smoking may alter epithelial lining fluid volume by reducing clearance or by stimulating production and, thus, affect the interpretation of bronchoalveolar lavage studies. In this study, urea was used as an endogenous marker of epithelial lining fluid volume in a comparison of 26 smokers and 31 nonsmokers. The mean epithelial lining fluid volume recovered from smokers was significantly greater than that of nonsmokers (2.4 +/- 1.40 ml vs 1.2 +/- 0.75 ml, p less than 0.005). The total cellular concentration in the bronchoalveolar lavage fluid in smokers was also greater (94.2 +/- 46 x 10(6) vs 33.9 +/- 21.5 x 10(6) cells per 300 ml lavage), even when corrected for bronchoalveolar lavage volume recovered (63.1 +/- 32.5 x 10(6) vs 24.9 +/- 13.3 x 10(6) cells per 100 ml recovered lavage fluid). This was true for macrophage, lymphocyte and neutrophil cell numbers. However, when corrected for the apparent epithelial lining fluid volume, only the macrophage count remained significantly higher in the smokers compared with nonsmokers (30.66 +/- 20.7 x 10(6) vs 18.21 +/- 8.6 x 10(6) macrophages.ml-1 ELF). In addition, concentrations of albumin and immunoglobulin M (IgM) were significantly lower in smokers after correction for epithelial lining fluid volume. These results highlight smoking as a confounding factor in the interpretation of bronchoalveolar lavage data.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of bronchoalveolar lymphocytes during a specific antibody-forming cell response in the lungs of mice

The goal of this study was to characterize the total numbers and phenotypes of lymphocyte subpopulations recovered by bronchoalveolar lavage during an experimental immune response in the lung parenchyma. Inbred mice (C57BL/6) were primed systemically and then challenged intratracheally with sheep red blood cells, a T-cell-dependent antigen. At various days later, we performed differential cell counts, measured the concentrations of specific antibody-forming cells, and determined lymphocyte phenotypes in bronchoalveolar lavage fluid by flow cytometry, distinguishing lymphocytes by light scatter parameters. We found that the numbers of lymphocytes recovered by bronchoalveolar lavage increased significantly in primed mice challenged with the priming antigen but not in three control groups: unprimed mice challenged intratracheally with the same dose of sheep red blood cells, primed mice challenged with hydrochloric acid, and primed mice challenged with a non-cross-reacting erythrocyte. At all times tested the concentrations of antibody-forming cells in bronchoalveolar lavages were identical to those of cells from minced lungs. Helper T-cells (L3T4-positive) increased earliest and constituted the majority of lymphocytes in bronchoalveolar lavage fluid throughout the immune response. We conclude: first, that there is a major influx of lymphocytes into the lungs during the development of a specific pulmonary immune response; second, that this lymphocyte influx occurs only in the presence of an antigen-driven response; third, that lymphocytes specific for the challenging antigen are in equilibrium between the bronchoalveolar and interstitial compartments; fourth, flow cytometry can be used to determine surface phenotypes of bronchoalveolar lymphocytes in mice.