Calcium-channel antibodies in the Lambert-Eaton syndrome and other paraneoplastic syndromes

Patients with the Lambert-Eaton syndrome may have predominance of antibodies of the P/Q type. P/Q-type antibodies are antagonists of a subtype of calcium channels that are responsible for abnormal cell behavior. Lambert-Eaton syndrome is a paraneoplastic disorder characterized by its own immune response against parts of tumor cells. Paraneoplastic syndromes, often associated with small-cell lung carcinoma, may contain the calcium channel subtypes L, N, and P/Q. Researchers searched for antibodies of these three subtypes in the blood samples of patients with cancer and other diseases. All 32 patients with the Lambert-Eaton syndrome and diagnosed cancer had autoantibodies specific for P/Q-type calcium channels. Also, 30 of 33 patients with the Lambert-Eaton syndrome but without cancer had P/Q-type calcium-channel antibodies. The N subtype appeared to a lesser degree in cancerous conditions.