Case report and literature review: transient Inab phenotype and an agglutinating anti-IFC in a patient with a gastrointestinal problem.

BACKGROUND: The Inab phenotype is a rare deficiency of all Cromer antigens. These antigens are carried on the decay-accelerating factor (DAF, CD55) molecule that is attached to the red blood cell (RBC) membrane by a glycosylphosphatidylinositol (GPI) anchor. Although typically inherited, an acquired and transient form of the Inab phenotype also exists. A patient with the triad of transient Inab phenotype, a direct-agglutinating anti-IFC, and gastrointestinal (GI) abnormalities is reported. CASE REPORT: An 18-month-old boy with gastroesophageal reflux disease requiring a feeding tube, milk and soy intolerance, and severe growth retardation, as well as vision and hearing deficits from cytomegalovirus infection, was identified when pretransfusion testing revealed a potent panagglutinin (titer > 2000 at 4 degrees C). This antibody did not react with Dr(a-) and IFC RBCs, and the autocontrol was negative. The patient's RBCs lacked CD55 by flow cytometric techniques but had normal levels of CD59 and antigens such as Yt(a) and Emm, carried on GPI-linked proteins, thus excluding paroxysmal nocturnal hemoglobinuria. Several months after initial detection, the anti-IFC was virtually undetectable and his cells reacted weakly with anti-IFC, anti-Dr(a), and anti-CD55. RBCs from the propositus' parents and brother demonstrated normal CD55 and CD59 expression. CONCLUSION: This is the first example of a direct-agglutinating anti-IFC. The cause of the transient depression in CD55 protein (and thus Cromer system antigens) and appearance of anti-IFC remains unknown, as does the relationship between the patient's GI system abnormalities and these serologic findings.

Exchange transfusion for malaria and Babesia infection.

Malaria accounts for about 2 million deaths per year. Although most cases occur in children in sub-Saharian Africa, fatal infections are seen increasingly in industrialized countries. In 1992, over 900 malaria cases were reported in the United States and a third of these were caused by Plasmodium falciparum. Fatal infections are related to the magnitude of the parasitemia and the immune status of the host. P falciparum poses the greatest threat of death because it invades red cells of all ages, is often drug resistant, and is the only one of the plasmodia species that produces microvascular disease. The risk of death is correlated with the parasite load in immune naive individuals. Babesiosis is generally a subclinical infection in most normal hosts, but it can be life threatening in asplenic patients, older, or immunocompromised individuals. The role of exchange transfusion (ET) in the treatment of these infections is controversial. The Centers for Disease Control recommends that ET be performed in P falciparum infection when parasitemia is equal or greater than 10%. In patients with coma, renal failure, or adult respiratory distress syndrome, ET is recommended regardless of the level of parasitemia even if less than 10%. ET has been advocated to reduce the level of parasitized red blood cells (RBCs), to remove cytokines, and to improve the rheologic properties of the blood. Dramatic improvement has been reported, but there are conflicting reports that question the need for exchange transfusion. This review examines the pathophysiology of severe infection and its treatment, with an emphasis on the role of exchange transfusion.