Welcome Dear Student

This blog was designed for the Biomedical Technology students at the Durban University of Technology, in Durban, South Africa. It consists of short notes on aspects that I feel that my students grapple with, and aims to provide a better explanation than that they would receive in lectures. It is also a very personal blog, where I feel comfortable 'talking' to my students.

Please email me sherlien@dut.ac.za




Search This Blog

Thursday, November 3, 2011

Error in CM

STUDENT NO 21123303
33 39 49 33 70 40.9

immunology course marks 2011

student TEST1 TEST2 PRAC1 PRAC2 Project CM
21110644 54 66 85 70 70 66.25
21001585 58 33 81 47 70 53.5
21001710 50 78 89 90 100 75.25
21141071 59 70 70 80 90 70.2
21008595 77 95 53 82 70 78.85
21108605 55 51 75 47 70 57.1
21008167 55 14 55 83 0 41.4
21014104 42 51 70 85 70 58.15
21014093 55 68 98 88 70 71.8
21001465 50 81 75 77 100 72.1
21113096 19 18 73 20 50 30.05
21103142 42 60 74 73 70 59.65
21123354 38 51 53 68 70 51.85
20908733 43 53 65 60 60 53.55
21107438 50 73 90 93 80 72.35
21141069 41 55 68 63 70 55.45
21120190 50 48 60 47 70 52.45
21014095 63 62 85 87 90 72.3
21014107 71 97 93 93 100 88.3
21004440 69 74 75 70 100 74.65
21009732 54 54 63 63 70 58.3
21014109 56 59 78 78 70 64.9
21005818 70 63 83 80 70 71.35
20902745 36 71 78 80 70 62.8
21108356 60 52 85 90 70 66.85
20906847 58 57 98 77 60 66.75
21130079 40 16 41 43 50 34.4
20936113 70 64 84 93 100 76.75
21109005 22 76 83 60 70 57.85
20905697 34 53 83 55 60 52.8
21123303 33 39 49 33 0 33.9
20907389 39 47 73 60 60 51.75
21111318 57 60 53 63 70 59.5
20900883 52 58 73 70 90 63.45
21013928 74 68 80 95 90 77.85
21103921 49 66 71 47 70 59.2
21017854 57 57 76 63 70 62.05
20907165 21 36 73 37 50 38.6
21014097 55 61 98 53 70 64.45
20903040 50 65 89 50 70 62.35
21008877 52 41 75 83 80 59.6
21104720 51 46 76 73 80 59.45
20900920 35 62 34 8 0 35.4
20920886 47 64 83 53 60 59.7
21110353 31 47 73 67 70 51.4
21139224 49 68 65 43 100 61.3
20924296 40 48 43 70 60 49.35
21011387 51 83 65 67 70 67
21000961 43 41 64 73 70 52.75
21030811 42 61 70 53 70 56.35

Wednesday, October 26, 2011

Monday, October 24, 2011

Wednesday, October 19, 2011

Functions of HLA antigens

Both MHC class I and II are involved in MHC restriction.

Both MHC class I and II are antigens targeted by the immune response in transplant rejection.
Some terms before we proceed:
Graft rejection refers to the recipients immune response rejecting the donor organ.
GVHD (graft versus host disease) refers to the transplanted organ mounting an immune response to the host's antigens. Sounds strange but GVHD is potentially fatal. That is why identification of Ag and Ab in both the recipient and donor is important.

HLA-A, HLA-B and HLA-DR are the main antigens targeted by the recipient, in graft rejection. If there are incompatibilities with these antigens, the feasibility of a successful transplant is low.

All MHC class II antigens are targets in GVHD.

Histocompatibility testing ideally should identify incompatibilities for both class I and class II. This will reduce the likelihood of both graft rejection and GVHD.

HLA and MHC

MHC is located on the short arm of chromosome 6. This locus codes for the HLA antigens that are found on various cells in the body. There are 3 classes of MHC.
MHC class I are found on platelets and all nucleated cells. examples of MHC class I are HLA-A, HLA-B and HLA-C.
MHC class II are found on macrophages, monocytes and lymphocytes. Examples are HLA-D, HLA-DP, HLA-DQ and HLA-DR.
Examples of MHC class III are C2, C4 and Factor B. (remember complement?)

We need to know the actual structures of MHC class I and II.
For each structure you need to know where antigen binds, and where CD4 or CD8 interacts. Remember that CD4 or CD8 are cell markers and are attached to cells, viz. TH and TC respectively. So do not draw just the cell marker; ensure that you draw the cell as well.
You need to know the names of each domain; these are not interchangeable and you will lose marks if they are labelled incorrectly.

Ag binds between alpha 1 and alpha 2, and CD8 interacts with alpha 3. (MHC class I)

Ag binds between alpha 1 and beta 1, and CD4 interacts with beta 2 (MHC class II)

Tuesday, October 18, 2011

TERMS in Ag Ab reactions

Titre refers to the concentration of a particular substance in a test tube.It is expressed by inverting the concentration of that substance. If the concentration of glucose is 1/16 in test tube no 4, the titre of test tube no 4 is 16.


A serial dilution is any dilution where the concentration decreases by the same quantity in each successive step.
double dilutions are a series of ½ dilutions. Each successive tube will ½ the amount of the original concentrated solution.
In any serological test done in the lab, we are looking for an unknown using a known. The known are the reagents that we use, usually commercialy available. The unknown is usually in the patients specimen, and can be either antigen or antibody.
Acute phase serum refers to specimen taken during the disease state, used to diagnose the disease.
Convalescent phase serum is taken after the disease has been treated, and can be used to determine if titre has decreased due to effective treatment.

Serum has no clotting factors present; usually specimen taken in brown top blood collection tube (with no anticoagulants)
Plasma has all clotting factors present; usually collected in purple top tube (containing anticoagulants)

Sterility is not an issue in serology as we are looking for presence of Ag or Ab. Any organisms present will not affect the results
Sensitivity refers to the ability of a serologicl test to identify the Ag or Ab in minute amounts. There will not be any false negative results due to the Ag or Ab being present in very small amounts.
Specificity refers to the ability of a serological test to identify the exact Ag or Ab being tested for. There are no cross reactions giving false positive results.

All serological tests have to be controlled. These controls are put up at the same time as the tests, and must give the correct expected readings/results before the test results can be taken as being accurate.Both positive and negative controls are used.
There is increasing automation in serology. Even in tests that are not automated, the equipment used are designed to save time and space. Microtitre plates replace test tubes. Slides with either Ag or Ab absorbed onto their wells save time in processing.Most procedures use very small amounts of substances/reagents. This saves money as reagents are usually very expensive.

Due to the precise and small amounts of reagents used in serological tests, serology requires the lab worker to be accurate and precise in their work. Amounts are not negotiable. any deviation from this will lead to inaccurate results.