This study will collect blood plasma and white blood cells for laboratory research using a procedure called apheresis. Apheresis is a method of collecting larger quantities of certain blood components than can safely be collected through a simple blood draw.

Patients 7 years of age and older with a parasitic infection or condition associated with a parasitic infection (i.e., elevated levels of IgE antibodies or of a type of white cell called eosinophils) who are currently enrolled in a NIH clinical research protocol may be eligible for this study. Relatives of patients and normal healthy volunteers will also be enrolled. Candidates will have a medical history, physical examination and blood tests. Individuals weighing less than 25 kilograms (55 pounds) may not participate.

Participants will undergo one of the following two apheresis procedures:

• Automated pheresis - Whole blood is drawn through a needle placed in an arm vein and circulated through a cell separator machine. The plasma (liquid part of the blood) and white cells are extracted, and the red cells are re-infused into the donor through a needle in the other arm. The procedure takes 1 to 2 hours.
• Manual pheresis - Whole blood is drawn through a needle placed in an arm vein and circulated through the cell separator machine. The red blood cells are separated from the rest of the blood and returned to the donor through the same needle. Usually only one needle stick is required and the procedure takes from 30 to 45 minutes. This method is used only in individuals who weigh less than 35 kg (77 pounds).

In order to carry out in vitro research procedures on the plasma or leukocyte components of blood, it is often necessary to obtain larger quantities of plasma, leukocytes, or platelets than can be safely obtained by simple phlebotomy. These components can be easily and safely obtained using apheresis procedures in the Clinical Center Apheresis Unit. This protocol is specifically designed to conform to the requirements of the Apheresis Unit for donors to have apheresis procedures (greater than 7 years of age and greater than 25 kg) but the protocol in itself is not a research protocol. Donors must first be admitted to another approved clinical research protocol of the NIAID before they may have the apheresis procedures described in this protocol.

• Leukopheresis
• Plasmapheresis

• Semnani RT, Liu AY, Sabzevari H, Kubofcik J, Zhou J, Gilden JK, Nutman TB. Brugia malayi microfilariae induce cell death in human dendritic cells, inhibit their ability to make IL-12 and IL-10, and reduce their capacity to activate CD4+ T cells. J Immunol. 2003 Aug 15;171(4):1950-60.
• Babu S, Nutman TB. Proinflammatory cytokines dominate the early immune response to filarial parasites. J Immunol. 2003 Dec 15;171(12):6723-32.
• Mitre E, Taylor RT, Kubofcik J, Nutman TB. Parasite antigen-driven basophils are a major source of IL-4 in human filarial infections. J Immunol. 2004 Feb 15;172(4):2439-45.

• INCLUSION CRITERIA:
• Enrolled on another LPD protocol.
• Weight greater than 25 kg
• Willingness to participate

EXCLUSION CRITERIA:

• Age less than 7 years
• Weight less than 25 kg
• Cardiovascular instability
• Hct less than 30
• Inadequate venous access
• PTT or PT greater than 1.5 normal
• Pregnancy
• Other condition which the attending physician or Apheresis Unit staff considers a contraindication to the procedure
• For Hetastarch procedure
• Hypertension
• Evidence of fluid retention