選択的IgM欠損症の1症例

Abstract

We report a case of selective IgM deficiency not associated with malig- nancies or autoimmune disorders. A 26-yr-old male was admitted because of acute bronchopneumonia. Cefmetazole was effective for the disease. He, however, seemed to have an impaired immunity against infections. Six and 3 months before this admission, he had been hospitalized with acute pleuritis. In addition, he had more histories of recurrent infections; 3 hospitalizations for pneumonia at 16, 20 and 21years of age, twice for pyelonephritis at 17 and 27 years of age and once for acute sinusitis at 8years of age. Laboratory findings revealed a very low level of serum IgM, 10 mg/dl, while serum IgG and IgA were within normal limits, 805 mg/dl and 239 mg/dl, respectively. Interestingly serum IgD was elevated as high as 102 mg/dl. On microfluorometric analysis of peripheral blood lymphocytes (PBLs), the number of B lymphocytes bearing pan-B markers such as CD 19, CD 20 and CD 21 was decreased, while that of CD 4⁺ or CD 8⁺ T cells and the CD 4/CD 8 ratio was normal. As for the number of B lymphocytes bearing surface immunoglobulin (sIg), the number of sIgM⁺ B lymphocytes was decreased. Responses of PBLs to both phytohemoagglutinin and concanavalin A were normal, but those to pokeweed mitogen and staphylococcus aureus Cowan strain I seemed to be suppressed. In the present report, we also discuss the cases of primary selective IgM deficiency documented in the literature.