Inclusion Criteria

- SUBJECT INCLUSION CRITERIA:

Healthy Volunteers must:

1. Be 18-60 years of age

2. Be healthy

3. Have adequate peripheral venous access

4. Have normal renal function (creatinine less than or equal to 1.5mg/dL; less than or
equal to 1 plus proteinuria)

5. Have normal hepatic function (bilirubin less than or equal to 1.5 mg/dL)

6. Have normal hematologic function (WBC greater than or equal to 3000/mm(3);
granulocytes greater than or equal to 1500/mm(3) ; platelets greater than or equal to
175,000; hemoglobin greater than or equal to 12.5 g/dL)

Patients must:

1. Be 18-60 years of age

2. Have mast cell hyperplasia compatible with a diagnosis of systemic mastocytosis
(applicable to systemic mastocytosis patients only) or other allergic, hematologic,
or immunologic condition

3. Have adequate peripheral venous access or be willing to have a central line placed.

4. First be admitted as inpatients under an existing NIH protocol

5. Have preserved renal function (creatinine less than or equal to 2 mg/dL; less than or
equal to 2 plus proteinuria)

6. Have preserved hepatic function (bilirubin less than or equal to 1.5 mg/dL)

7. Have preserved hematologic function (WBC greater than or equal to 3000/mm(3);
granulocytes greater than or equal to 1500/mm(3) ; platelets greater than or equal to
175,000; hemoglobin greater than or equal to 12.5 g/dL)

All female subjects of childbearing potential:

1. May be enrolled if using effective contraception

2. Have a negative serum or urine pregnancy test determined before beginning Plerixafor
or G-CSF administration

SUBJECT EXCLUSION CRITERIA:

All subjects must not meet any of the following criteria:

Healthy volunteers and patients must not:

1. Have active bacterial, fungal or viral infections

2. Have viral screens positive for HIV or hepatitis B or C

3. Be pregnant or lactating

4. Have a history of autoimmune disease such as rheumatoid arthritis, vasculitis,
pyoderma gangrenosum or similar disorder

5. Have any condition, which in the judgment of the investigator, might place the
subject at undue risk

Healthy Volunteers with any of the following will be excluded:

1. Splenomegaly, pulmonary fibrosis and other related conditions

2. Use of any investigative drugs within the past 12 months

3. Have a significant coagulation disorder

Systemic Mastocytosis and Mast Cell Related Condition Patients with any of the following
will be excluded:

1. Patients taking any other growth factors, cytokines or investigative drugs

2. Patients who are hemodynamically unstable (blood pressure systolic of lower than 105
or diastolic lower than 65)