A Case of IgM Deficiency with B Cell Deficiency Detected by ABO Discrepancy in a Patient with Acute Osteomyelitis
A 16-yr-old boy presented at our hospital with a 5-day history of intermittent and diffused pain in his right knee after exercise. He had no history of previous trauma or infection. On physical examination, he experienced pain upon motion of the right knee, with mild swelling and anterior knee tenderness.\nLaboratory examination revealed leukocytosis (11.7×109/L), a hemoglobin level of 13.1 g/dL, and a platelet count of 297×109/L. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were elevated at 76 mm/hr (reference range: 2-10 mm/hr) and 51.7 mg/L (reference range: 0-5 mg/L), respectively. The rheumatoid factor (RF) level was 24.6 IU/mL (reference range: 0-14 IU/mL). The results of liver and kidney function, serum electrolyte, alkaline phosphatase, and antinuclear antibody testing were unremarkable. Culture studies from blood specimens showed negative results for bacteria, fungus, and tuberculosis.\nDuring routine ABO blood grouping, cell type by the slide method was O+, but serum typing by the tube method detected only anti-A (3+). Anti-B was not detectable at room temperature but was graded at 1+ at 4℃. We performed several studies to define the cause of this discrepancy. Antibody screening test using LISS/Coombs gel (DiaMed-ID; Bio-Rad Laboratories, DiaMed GmbH, Cressier FR, Switzerland) did not detect any antibodies in the patient's serum. Adsorption and elution testing revealed no A or B antigens, and transferase test was negative. The isoagglutinin titers for anti-A and anti-B by the tube technique were 32 (control: 128) and 2 (control: 1,024), respectively. To confirm his blood group type, ABO genotyping was performed. The result revealed an O/O allele using the SNaPshot multiplex kit (Applied Biosystems, Foster City, CA, USA) according to a previously described method []. Serum IgG, IgA, and IgM concentrations were 770 mg/dL (reference range: 800-1,700 mg/dL), 244 mg/dL (reference range: 100-490 mg/dL), and 13.5 mg/dL (reference range: 50-320 mg/dL), respectively. Total protein and albumin were 70 g/L and 43 g/L, and the results of protein electrophoresis were unremarkable.\nMagnetic resonance imaging (MRI) showed decreased bone marrow signal at the distal femoral metaphysis and anterior crucial ligament tibial attachment (). The technetium 99m-hydroxymethylene diphosphonate (Tc-99m HDP) 30mCi bone scan showed increased uptake only in the metaphysis of right femur (). The symptoms gradually improved within 3 weeks after treatment with antibiotics (ceftizoxime), nonsteroidal anti-inflammatory drugs, splinting, and bed rest. His ESR and CRP levels retested at the end of this period and displayed normal values.\nSix months after recovery, ABO discrepancy and low levels of serum IgM persisted. Specifically, serum IgG, IgA, and IgM concentrations were 721 mg/dL (reference range: 700-1,600 mg/dL), 183 mg/dL (reference range: 70-400 mg/dL), and <16.8 mg/dL (reference range: 40-230 mg/dL), respectively. Complete blood count (CBC) was within the normal limit and RF level was 22.9 IU/mL (). Additionally, lymphocyte subset analysis was performed by flow cytometry (Beckman Coulter, Fullerton, CA, USA) and the results showed CD19+ B cell deficiency ().