Serum Samples
Most tests are performed on serum separated at room temperature. The exceptions are listed below. For serum, blood should be collected in a plain brown top gel tube with no anticoagulant. In most cases samples should be sent to the main pathology sample reception area level 2(external) or level 4 (internal) of the laboratory block at Addenbrookes Hospital, by porter, courier or hospital transport. Serum samples can also be sent by first class post to Clinical Immunology, Box 109, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 OQQ or Hayes DX(6050105 Camb 90 CB)
Allergy testing
The specific allergen required must be clearly stated.
Where mixes of multiple varieties are available, they will be used unless a specific allergen is requested e.g. Grass mix performed, unless 'Timothy grass' is specificified.
If the request is unclear Immunology at CUH may perform general food allergy testing, although it cannot accept responsibility for any choices made.
A request for Aspergillus will receive IgE, unless IgG Aspergillus is clearly stated.
If total IgE measurement is required, it must be clearly requested.
Lymphocyte Phenotyping Studies
These are performed on a 2.7 ml EDTA (Monovette) sample
Cytokine studies
Please send from Patient and from a healthy control:
5-10 ml Li-heparin blood (3 ml from very small children)
2.7 ml ETDA-blood
1-2 ml Serum/clotted (not for very small children)
Samples must be sent by courier at ambient temperature (please do not cool and avoid overheating)
Discuss with the laboratory via the service desk before sending.
Immunoglobulins
Routine tests for total serum IgG, IgA and IgM are performed in the Clinical Biochemistry.Tests for IgG subclasses and total IgE are performed in the Clinical Immunology laboratory.
Functional Complement Studies including Functional C1 inhibitor
Blood taken at Addenbrooke’s Hospital for these assays should reach the laboratory within 30 minutes of being taken and labelled as being urgent. (Do not rely on routine collections!) It should then be separated and frozen to a temperature of at least -40oC within a further 30 minutes. External laboratories must also ensure correct collection of the blood and arrange for it to reach this centre while still deep-frozen. If these procedures are not followed then abnormal low values could be due to in vitro degradation.
Functional C1 inhibitor assays should only be performed after initial screening for immunochemical C1 inhibitor concentration in cases where there is a documented normal value of inhibitor but the C4 is low.
Mast Cell Tryptase
Blood taken for Mast Cell Tryptase levels should be centrifuged and the serum separated as soon as possible, preferably within 3 hours of venesection. If the blood is collected into gel separator type tubes centrifugation alone is sufficient. The separated serum or spun tubes should be kept at 4oC and sent to Addenbrookes Immunology.
If the samples will not reach Immunology at Addenbrookes within 5 days then separated serum should be frozen at -20 oC or below and then dispatched in a frozen state.
If the sample(s) have been taken as part of an anaphylactic/anaesthetic reaction investigation then it is vitally important that sample time and dates are accurately recorded on both sample and request
Beta Trace protein (Tau)
Samples for Beta Trace protein (Tau) which are 'fluid' thought to be CSF (from nose or ear) can be collected in universal containers or small sample tubes with no gel/preservative.
Urine
Requests for Bence Jones protein require a 20ml aliquot of urine in a universal container (NO preservative).
To ensure safe and accurate results, the following cut off times for receipt of certain sample types will apply;
Neutrophil Function Studies
Neutrophil oxidative burst DHR tests are performed on a 2.7 ml EDTA (Monovette) sample taken directly to the laboratory or transported to arrive in the laboratory within 4 hours of collection, along with a control sample. Neutrophil tests are time consuming, and can only be done on Monday to Friday if received before 2.00 pm.
Quantiferon TB Gold (Interferon gamma release assay-IGRA)
Adults and children: 1ml of blood must be drawn directly into each of the four QuantiFERON-GOLD Plus tubes in order, which must be all labelled with appropriate patient identifying information. These tubes contain specific antigen and can not be substituted for alternative tubes.
(1) Nil control (GREY TOP)
(2) TB 1 Antigen (GREEN TOP)
(3) TB Antigen 2 (YELLOW TOP)
(4) Mitogen Control (PURPLE TOP)
(Collection tubes available from outpatients Phlebotomy and directly from the Immunology laboratory)
Samples must be incubated at 37º c within 16 hrs of collection, and must be kept at room temperature prior to this. Samples to be received in the Immunology laboratory by 16:00 Monday to Friday.
Please contact the laboratory for further information if requesting test from non-Addenbrookes locations.
Cryoglobulins
If cryoglobulins are suspected in autoimmune rheumatoid disorders, a 10 ml blood sample should be collected in a pre-warmed plain white Monovette tube and placed immediately into a vacuum flask containing water at about 37°C. The sample should be immediately delivered to the Clinical Immunology Laboratory by 16:00 Monday to Saturday. Please call 01223 216511 to collect a validated 37°C flask for transport.
Please contact the laboratory for further information if requesting test from non-Addenbrookes locations.
Urgent MPO/PR3/GBM
Urgent MPO/PR3/GBM requests – Please confirm with Laboratory before dispatch and sample to arrive in laboratory no later than 15:30 Monday to Saturday.
Storage of Specimens
Sera are stored at 4°C, other than functional complement samples, and retained for about 2-3 weeks before disposal. If further tests are required on a patient in the light of earlier results, it may be possible to save the inconvenience of a repeat venesection for the patient by contacting the laboratory and arranging further tests on the stored serum. Specimens for cellular immunology tests cannot be retained and follow on tests cannot be added after the time of the initial testing.