Automated method for direct sampling of immune cells from whole blood or other biological samples in microwell plates
The present disclosure provides a method for automatic sampling of immune cells from a biological fluid sample, e.g., whole blood, deposited in a well of a microwell plate. The microwell plate is placed on a shaker having a magnetic adapter including at least one magnet. The magnet causes red blood cells (RBCs) bound to magnetic beads to be attracted to and migrate to a wall of the well. The shaker is then operated to shake the microwell plate such that the immune cells are substantially isolated from the RBCs in a region of the well. A sample probe is then lowered into the region of the well to withdraw a portion of the sample containing the immune cells.
1. A method for automatic sampling of immune cells from a biological fluid sample deposited in a well of a microwell plate, the well having a wall, the biological fluid sample containing (1) red blood cells (RBCs) and (2) magnetic beads which are designed to bind to the RBCs in the sample, comprising the steps of:
a) placing the microwell plate on a shaker having a magnetic adapter including at least one magnet, wherein the magnetic adapter is removably coupled to the shaker and the microwell plate is removably coupled to the magnetic adapter, wherein the magnet causes the RBCs bound to the magnetic beads to be held against the wall of the well, wherein a shield comprising a ferromagnetic material is affixed to a bottom surface of the magnetic adapter such that the shield does not directly contact the at least one magnet, wherein the shaker further comprises a sensor, and wherein the shield is configured to shield the sensor from a magnetic field created by the at least one magnet;
b) shaking with the shaker the microwell plate in a manner and for a time period so as to suspend the immune cells in the biological fluid sample within a region of the well such that the immune cells are isolated from the RBCs held against the wall of the well; and
c) lowering a sample probe into the well in the region of the well and withdrawing a portion of the sample containing the immune cells from the region.
2. The method of claim 1 , wherein the magnetic adapter comprises a structure holding individual magnets, one for each well of the microwell plate, wherein the magnetic adapter is configured to fit onto an upper surface of the shaker and be sandwiched between the upper surface and the microwell plate, and wherein the magnets cause the RBCs to be held to a bottom wall or a side wall of the well.
3. The method of claim 1 , wherein the biological fluid comprises whole blood.
4. The method of claim 1 , wherein the biological fluid comprises a cyst fluid sample, amniotic fluid, a bone marrow sample, a cerebrospinal fluid sample, a liquid biopsy, or a chorionic villus sample.
5. The method of claim 1 , wherein the sample probe is part of a flow cytometer, and wherein the method includes step d) of introducing the portion of the sample containing the immune cells into the flow cytometer.
6. The method of claim 1 , wherein the sensor comprises a home position sensor.
7. The method of claim 1 , wherein the shaking step comprises the step of operating the shaker in an eccentric rotation at a speed of between 100 rpm and 1500 rpm.
8. The method of claim 1 , wherein the magnetic beads comprise magnetic or paramagnetic beads with an estimated size between 1 nm-50 μm, conjugated with a specific molecule that binds to a molecule expressed on the RBCs but not on the immune cells.
9. The method of claim 1 , wherein in step a) and c) the shaker is in a non-shaking condition.
10. The method of claim 1 , wherein the magnetic adapter including the at least one magnet is integrated into the shaker.
11. The method of claim 1 , further comprising the step of placing a pierceable seal over the microwell plate prior to performing step a).
12. The method of claim 1 , wherein the sample further includes in-well marker beads or in-well counting beads.
13. The method of claim 1 , wherein the magnetic adapter includes at least one recessed pocket, and wherein each of the at least one recessed pocket includes a given magnet of the at least one magnet.
14. The method of claim 1 , wherein in step a) the shaker operates in an eccentric rotation at a first speed, wherein in step c) the shaker operates in an eccentric rotation at a second speed, and wherein the second speed is greater than zero but less than the first speed.
15. The method of claim 1 , wherein the shaker includes a first pair of locating pins projecting from an upper surface of a first corner of the shaker and configured to contact a first corner of the magnetic adapter, wherein the shaker includes a second pair of locating pins projecting from the upper surface of a second corner of the shaker and configured to contact a second corner of the magnetic adapter, and wherein the first pair of locating pins and the second pair of locating pins are computer-controlled to move into and out of a gripping position to grip the magnetic adapter to thereby hold the magnetic adapter in place.
16. The method of claim 15 , wherein the first corner of the magnetic adapter is positioned diagonally opposite from the second corner of the magnetic adapter.
17. The method of claim 15 , wherein a third corner of the magnetic adapter includes a first corner feature and a fourth corner of the magnetic adapter includes a second corner feature, wherein the third corner is diagonally opposite the fourth corner, and wherein the first corner feature and the second corner feature are designed to hold the mircrowell plate in place.
18. The method of claim 15 , wherein the magnetic adapter includes a first pair of recesses configured to receive the first pair of locating pins, and wherein the magnetic adapter includes a second pair of recesses configured to receive the second pair of locating pins.
19. The method of claim 1 , wherein a first side of the magnetic adapter includes a first resilient gripping skirt extending down from a bottom surface of the magnetic adapter, wherein a second side of the magnetic adapter includes a second resilient gripping skirt extending down from the bottom surface of the magnetic adapter, wherein a first side of the shaker includes a first recess configured to receive the first resilient gripping skirt of the magnetic adapter, and wherein a second side of the shaker includes a second recess configured to receive the second resilient gripping skirt of the magnetic adapter.