4 Abstracts J. ALLERGY CLIN. IMMUNOL. AUGUST 1982

specific antagonists were added to the muscle bath after the contractile effects of the agonists and the macrophage debris were measured. The macrophage product-induced contrac- tion lasted over 30 min and was equal to the tension induced in guinea pig smooth muscle by 40 f 19 rig/ml Met, Atr, Mep, and Cim did not antagonize the macrophage product reaction. Ind enhanced the induced smooth muscle con- striction, while the constriction could be abolished com- pletely by adding FPL 557 12 to the bath after the smooth muscle was constricted by the macrophage debris. The FPL 55712 effect was mimicked by changing the muscle strip bath pH value toward the acid side (pH 5.5), demonstrating that the macrophage material exhibited SRS lability in an acid medium. The effect was unchanged in an alkaline medium. Pharmacologic implications of SRS antagonism are discussed.

D. S.

Clinical applicability of a methacholine inhalational challenge

Myers JR, Corrao WM, Braman SS: JAMA 246:3, 1981.

Of 324 patients who underwent methacholine inhalation challenge, eight positive responders are described in this article because of the diagnostic difficulties they presented.

The authors used a standard spirometer to measure forced vital capacity, forced expiratory volume (FEV), and maxi- mum midexpiratory flow rate (Mh4EFR). After baseline measurements, increasing concentrations (from 5 to 25 mg/ml) or increasing numbers of inspired breaths (one to four) of aerosolized methacholine chloride were adminis- tered. Five dose units of the agent were taken as the total dose of one breath of a 5 mg/ml concentration. A 20% or more fall in FEV was considered to be a positive response, while a less than 20% drop in FEV with the high dose (200 dose units) was considered to be a negative response.

One patient presenting with episodic dyspnea and cir- cumoral paresthesia was thought to have hyperventilation syndrome. Two individuals presenting with dyspnea asso- ciated with exertion (EIB) had normal standard pulmonary function tests (PFTs). Another patient with kyphoscoliosis and dyspnea had restrictive lung disease. One woman had biopsy-proven sarcoidosis and decreased MMEFR but no other finding of either restriction or obstruction on PFT. Two other patients complained of chronic cough of unde- termined etidogy, and a final patient presented with chest pain that increased during or after exercise and was associ-

ated with EIB. All eight patients had positive responses to the methacholine challenge. In addition, all the symptoms subsided with various types of bronchodilator therapy.

The authors stress that positive methachohne challenge responses can be seen in chronic obstructive bronchitis, al- lergic rhinitis, cystic fibrosis, status post-adult respiratory distress syndrome, and sarcoidosis, in addition to bronchial asthma. Transient positive methacholine challenge re- sponses are seen in certain patients with viral upper respira- tory tract infections. It is believed that a standardized meth- acholine inhalation challenge should be used to demonstrate bronchial hyperreactivity in cases where the diagnosis of asthma is not clear.

Robert Y. Lin

lmmunomodulating properties of dimethylglycine in humans

Graber CD, Goust JM, Giassman AD, Kendall R, Loadholt CB: J Infect Dis 143:lOl. 1981.

Dimethylglycine (DMG) is a tertiary amino acid that has been used as a dietary supplement. DMG is a hydrolytic product of pangamic acid, a substance suggested to have immunoadjuvant properties in irradiated animals. Lympho- cytes from normal subjects and from sickle cell and diabetic patients were stimulated with various mitogens with and without preincubation in DMG. A significant increase in blast transformation was observed in the DMG-preincu- bated cells of all the groups compared with the respective controls.

In another experiment subjects were fed either 120 mg of DMG together with 180 mg of calcium gluconate or 300 mg of calcium gluconate alone as a control over a 10 wk period. During this time each group was vaccinated with Pneu- movax. A greater rise in hemagglutinating antibody after vaccination was noted in the DMG-treated group. Leuko- cyte inhibitory factor (LIF) production using streptokinase- streptodomase (SK/SD) or concanavalin A as white blood cell stimuli were also examined in the same two groups before and after Pneumovax vaccination. Greater LIF produc- tion was observed in the DMG-treated group whose cells were stimulated with SK/SD. This relative increase in LIF was found both immediately before as well as after vaccination.

In view of these demonstrated immunomodulating effects of DMG, the authors encourage further research on the possi- ble role of DMG in enhancing immune response to tumor vaccines and to vaccines for specific infectious agents.

Robert Y. Lin