We present here a rare case that involved the long-term coexistence of 2 mature, functional, and equilibrated immune systems in a single child after fetofetal transfusion between dizygotic twins. A dichorionic diamniotic pregnancy complicated by twin anemia-polycythemia sequence resulted in the demise of 1 twin. The detection of abnormal vessels on the dichorionic plate strongly suggested the existence of functional vascular anastomoses leading to blood chimerism in the survivor. Genetic, phenotypic, and immunologic analyses at 2 years revealed chimeric lymphoid and myeloid cells in the surviving twin, although no tissue mosaicism was detected, which indicates that early transfusion led to mutual immune tolerance.
Dr Scarano's point regarding potential bias introduced by red blood cells (RBCs) in the cerebrospinal fluid (CSF) is well taken. Review of the actual numbers of RBCs in the CSF shows that 50.5% of patients had <5 cells/mm3 and an additional 23.5% had <100 cells/mm3 and only 4.2% had >500 cells/mm3. We excluded all patients with "bloody taps," which we defined as >1000 RBCs/mm3 in the CSF. Since the majority of patients had less than 100 RBCs in their CSF, we feel that the potential for bias resulting from blood contamination of the CSF is minimal.
The first issue raised by Gordon—the "problem of the [unexpectedly] dry myringotomy" suggests a misreading of the stated conditions of our study. The subjects were not our patients, but were patients whose cases were being managed by other physicians who allowed us to study them. And the diagnostic assessments—both otoscopic and tympanometric—were carried out immediately preoperatively. Thus few of the "dry taps" were unexpected: rightly or wrongly, most of them were performed knowingly in order to insert tympanostomy tubes in an effort to prevent recurrence of acute otitis media1 rather than to remove middle ear effusion.
Paradise et al. make no mention of the important but largely ignored clinical problem of the dry myringotomy, as occurred in a third of the ears they tested (Pediatrics 58:198, August 1976). Most of these bilaterally dry taps would be avoided if immediate preoperative reassessments were routinely performed to exclude those whose effusions had spontaneously cleared since being scheduled for operation. Anesthesia is not hazardless, so there is surely a serious ethical problem when this retesting is not done, unless a therapeutic or diagnostic grommet is inserted regardless.
"DAS ERSTE TRIMENON" was the title of a lecture given by Ernst Moro (Fig. 1) on May 7, 1918, before a meeting of the Society of Natural History and Medicine in Heidelberg; in this lecture the speaker discussed some features peculiar to the first 3 months of an infant's life.1 At the end of it "almost as an afterthought,"2 Moro described what he called "a small observation": When a young infant is placed on the examining table and one taps with the hands on both sides of the pillow there follows a peculiar motor reflex: both arms are symmetrically extended and then approach each other again with slight shaking movements.