CD1 molecules

Question 1

What chromosome are MHC and CD1 on?

Answer 1

MHC on chromosome 6, CD1 on chromosome 1

Question 2

How many groups of CD1 in humans? What ones in each?

Answer 2

Group 1: CD1a, b and c (and e). Group 2 is CD1d.

Question 3

Do mice have CD1?

Answer 3

Only group 1 CD1 (and is it a psedo gene?)

Question 4

what is strucutre of CD1 moelucels like? More similar to the MHC I or II?

Answer 4

CD1 has a1, a2 and a3 domains that are coupled with B2 micoglobulin.

Question 5

Differences of CD1 to MHC?

Answer 5

monomorphic (not polymorphic), unlike MHC haplotypes where unlikely two individuals have the same. Hihgly likely we have same CD1.

Question 6

What kind of cells bind to CD1 a, b and c?

Answer 6

T cells (mostly double negative) that have adaptive like responses.

Question 7

What kind of cells bind ot CD1d and what kind of response?

Answer 7

iNKT cells bind to CD1d and have innate like responses.

Question 8

what antigens do CD1 molecules present?

Answer 8

They present lipids in a deep hydrophobic groove, notpeptide antigens.

Question 9

Sturucutre of lipids?

Answer 9

glyceride (sugar moiety) and a long hydrocarbo chains which are hydrophobic.

Question 10

Is expression of CD1 and type of antigen CD1 presents more like MHC 1 or 2?

Answer 10

CD1 is restricted to APCs (DCs, monocytes, IECs and Bcells) and presents exogenous antigens like MHC II.

Question 11

Do they use the TAP transporter for loading or lysosoal acidification pathway for loading?

Answer 11

Like MHC II molecules, CD1 antigen presentation doesn’t require TAP, but does use lysosomal acidificatino.

Question 12

What ligands fill the CD1 groove in ER and Golgi and at the surface?

Answer 12

Self lipids will fill the CD1 upon initial presentation.

Question 13

What class of CD1 stays at the surface to present exogenous (and self) antigens?

Answer 13

CD1a has motif (or lacks motif) that means it swaps self ligand for exogenous ligands on cell surface.

Question 14

Which classes of CD1 can progress to the endosome and lysosome? Why do we need different CD1s?

Answer 14

CD1c and d can progress to the endosome, and CD1d can progress to the lysosomal compartments.
Means CD1 present to monitor different compartments to sample more complex lipids that progress through each compartment. Diversity to compensate for monomorphic nature.

Question 15

What enzymes is improtat for lipid loading to CD1 molecules in the ER? and in the endosomes/lysosomes?

Answer 15

MTP in the ER helps offer lipids. IN endosome/lysosome saposins do this or soluble CD1e.

Question 16

How do binding grooves of CD1 molecules differ?

Answer 16

Differ by size, smallest is CD1a C36 and largest is CD1b C72. Average self lipid is CD30, so larger lipids are hallmarks of infection.

Question 17

How can viruses affect CD1? But do viruses have lipids?

Answer 17

decrease CD1 transcription, interfere with secretion pathway, increase their endocytosis and promote their degradation.
However, viruses do not have lipids?

Question 18

What kind of antigens can group 1 specific T cells recognise?

Answer 18

They recognise autoantigens as well as microbial antigens.

Question 19

What co-receptors are group 1 restricted T cells often missing?

Answer 19

They were missing CD8 or CD4 expression.

Question 20

What are germline-encoded mycolyl reactive TCR T cells? What kind of infections are they found in?

Answer 20

GEM T cells are conserved across individuals that are CD1b restricted and recognise mycolyic acid.
Found in mycobacterial infections.

Question 21

When putting T cells together with APCs expressing CD1a and CD1b and d, what kind of T cells were found?

Answer 21

Found that there were CD1a and CD1c aB and yD cytotoxic lymphocytes that were produced.

Question 22

Endogenous self lipids can be targeted by autoreactive CD1 restricted T cells. What T cell responses might you get?

Answer 22

Might generate some CD1 restricted immunoregulatory responses.
But mostly get pathogenic CD1 restricted Th17 and Th1 responses and autoantibody production.

Question 23

What tissue and cells have high expression of CD1a on APCs?

Answer 23

In the skin, Langerhans cells have high CD1a expression/

Question 24

What kind of T cells were found in the blood that might localise to the skin?

Answer 24

CD1a restricted T cells expressing chemokine receptors for skin-homing were enriched in blood. But these were CD4+.

Question 25

What kind of short and long lipids, in general, could be presented by CD1a in the skin?

Answer 25

shorter lipids were activating and longer ones were inhibitory.

Question 26

How can shorter more activatory self ipids be generated in the skin?

Answer 26

By phospholipases, introduced e.g by B sting, or by dust mites etc. this activates CD1a restricted T cells that initiate inflammatory responses.

Question 27

Two ways CD1a presentation be involved in contact dermatitis?

Answer 27

reactions to poison ivy may be lipid-based, as urushiol can bind to CD1a and be recognised by CD1a restricted urushiol reactive T cells.

Similar mechanism. but for balsam oils that fit into CD1a groove in commercial products.

Question 28

How might CD1b and c self-reactivity may be beneficial?

Answer 28

In CD1b and c mediated antitumour responses. Leukemic B cells can express higher levels of melanoma lipophosphatidic acid, that becomes a target of CD1c restricted cells.

Question 29

What do unconventional T cells still have? But are more restricted and less diverse?

Answer 29

iNKT, MAIT and yD T cells all have rearranged TCR. But they are restricted to antigens presented by monomorphic CD1d, MR1, and have lower diversity.

Question 30

Are unconventional T cells dependent on TCR for activation?

Answer 30

no, can be activated independently of TCR as well.