Quantitation of immunoglobulins produced by donor lymphocytes in transplant patients and the possible identification of donor cell-produced antiviral antibodies by imprint immunofixation

Microchimerism in immune competent patients related to the leukocyte content of transfused red blood cell concentrates

BACKGROUND

Microchimerism may play a part in transfusion complications. The aim of this study was to examine whether establishment of post-transfusion microchimerism was related to leukocyte content.

METHODS

Twenty non-pregnant female patients, without known malignant or immunological diseases, mean age 68 years, receiving 2-4 units of red blood cell concentrates during elective surgery, were included. One or two of the units were from male donors. Ten patients received buffy-coat depleted red blood cell concentrates, leukocyte count 108-109 per unit, and 10 patients received red blood cells leukoreduced by prestorage leukocyte filtration, with a leukocyte count of <106 per unit. EDTA samples were collected in vacuum tubes before and after 1 week and 6 months after transfusion. The tubes were frozen and stored at -400 degrees C. Genomic DNA was isolated and PCR performed using four primer sets amplifying markers on the Y-chromosome.

RESULTS

Microchimerism was detected in a total of eight out of the 20 patients. In three patients microchimerism was detected only before transfusion. These patients had given birth to one or two boys each, and had no history of previous transfusion. Two patients receiving buffy-coat depleted red blood cell concentrates and two patients receiving leukoreduced red blood cell concentrates had detectable microchimerism 1 week after transfusion. The age of the transfused red blood cell concentrates was 6, 24, 8 and 7 days, respectively. One patient receiving leukoreduced red blood cell concentrates had detectable microchimerism after 6 months. The age of this concentrate was 22 days.

DISCUSSION

This study demonstrates that microchimerism after transfusion does not seem to be dose dependent, and can be induced even by a >3 week old leukoreduced red blood cell concentrate with a very low leukocyte content.

Transfer of specific immunity from donor to recipient of an allogeneic bone marrow graft: evidence for donor origin of the antibody producing cells

A rapid recovery of specific humoral immunity in the recipient of an allogeneic bone marrow transplantation (BMT) can be observed after immunization of the donor before graft sampling. This has been attributed to transfer of specific immunity from donor to recipient. However, to maintain the concept of transfer the origin of the antibody producing cells in the recipient after BMT must be demonstrated. To this end, donor-recipient pairs with differences in Gm-allotypes were selected and immunized before BMT with the neo-antigen Helix pomatia haemocyanin (HPH) according to three immunization protocols. Additionally, the recipients were immunized at day 42 after BMT. Serum samples were weekly obtained from the recipients in the first 100 d after BMT. The origin of HPH-specific antibody producing cells was assessed by two approaches: (1) determination of the Gm-allotypes of anti-HPH antibodies within a distinct IgG subclass, (2) analysis of anti-HPH antibody spectrotypes by isoelectric focusing combined with immunoblotting. The results obtained with these two approaches show concordance in most instances and led to the conclusion that the antibody producing cells are of donor origin.