Does organic food helps my baby immune system?

It doesn't. It is inherently the same food as the normal food except that it is probably cleaner with lesser amount of pesticides / insecticides / fertilizer. It does not confer more nutrients of any sorts. Only genetically modified food contains the something extra - whatever the extra maybe depends on what was the modified component. Eating organic or not eating organic is not going to increase or decrease ur child's immunity - there is no clear cut conclusive studies of the benefits just yet. This eating of more "dirty" food - some people believe will improve immunity - yet that is also mostly baseless - because we are not pest/insect/weed and we are just exposed to a v small amount of it actually