BBeing ADAPTIVELY immune- eing ADAPTIVELY immune- Where did it come from???Where did it come from??? BBeing ADAPTIVELY immune- eing ADAPTIVELY immune- Where did it come from???Where did it come from???

Sandeep Satapathy,Roll-10079

Sandeep Satapathy,Roll-10079

Innate ImmunityNon pathogen specific Immune responseImmediate response

No memory of pathogenecity

Both in vertebrates and Lower Organisms.

Adaptive ImmunityPathogen specific

Immune response.

Delayed response .

Memory ofpathogenecity.

Only in Higher Organisms and Vertebrates.

Hypothesis:

Results

Where did the adaptive

molecules come from?

How spontaneous is this

evolution?

Were there any precursor

cells,which were initially non-immune cells?

Mostly the adaptive immune molecules arose from the

innate molecules with few exception like C3,MHC,TdT.

Adaptive molecules evolved abruptly and

isolating their precursors is tedious.Molecules with

different alias/function

evolved partly to be immune molecules

while other retained their identity.

Adaptive molecules/CellsB Cell Receptors (Ig)T Cell Receptors(TCR)

Major Histocompatibility

Complex (MHC)Recombination

activation Gene(RAG)Terminal dinucleotide transferases(TdT)

Complement System

C3,Factor B,Factor D-

Alternative CS-Innate

MASP-Lectin CS-Innate

C1,C4,C2-Classical-Adaptive

Innate Immune System-

Macrophages, NK cells, Nuetrophils,Eosinophils,

Dendritic Cells

Ig(BCR) and TCR Evolution:

Ig and TCRs(have high structural similarity)- belong

to the Ig superfamily.

RAGS and TdTs- accommodate variability in these lymphocytic receptors- maximise antigenic

determinants recognition.

Direct ancestors of Igs and TCRs were similar to the Ig superfamily of NK cells in mammals-

Innate precursors in higher organisms.

Also precursors were similar to Ig superfamily of NITR family found in invertebrates and bony fish-

Innate precursors in lower organisms.

Horizontal Gene Transfer

Precursor of RAG RAG-1&2

Precursor of TdT

TdTs

No distinct immune Function

Distinct lymphocytic receptor

recombination

MHC Evolution: A short evolutionary dwell

Many diverse group of molecules (classical and non classical) with both innate and adaptive immune functions.These molecules dwindle for different

functions in very short evolutionary timescale.

MHC Class II molecules evolved first from precursors, like DM genes .

Precursor of MHC II

e.g DMInvolved in antigen

processing

MHC IIMainly act as chaperons for

antigen presentation.

Complement Cascade Evolution:

Adaptive

Innate

Non-immune precursors(Alpha-2-

Macroglobulin-serine protease inhibitor)

(Alternative CS)

(Classical CS)

Lectin CS

Conclusion:

Innate Immune molecules

Non-immune cells

Adaptive Immune system molecules

Dragged force Evolution with few functionally

divergent evolution and other function and pattern

retaining conserved evolution.

Co-evolution with higher structural similarity and functional polymorphism. Frequ

ent

Rare

Both in Lower and higher organisms.

Only vertebrates and higher organisms.

Thank you all..........